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Pyrology, or Analysis and Synthesis by the Blowpipe. (CHEMICAL NEWS, pearance, and to have a grey granular fracture. It is the extreme range of the mercurial thermometer, but so now, we ourselves find, perfectly opaque to light, even in much beyond that it is still diminishing when, owing to the thinnest films. Its specific gravity has increased to the rapid volatilisation of the selenium, it has been found 4796. When heated it does not soften, but at 217° fuses necessary to terminate the experiment. without taking any intermediate pasty condition. At 250° It has hitherto been assumed that there is but one it is perfectly fluid, even when the mass is considerable ; granular form of selenium, and that this is a conductor and when rapidly cooled returns, without any tendency of electricity. We have, however, obtained a granular to crystallise, to the vitreous, non-metallic modification. form in no way optically differing from granular selenium All that has up to the present been made known as to of comparatively low resistance, through a rod of which, the electrical relations of selenium may be very shortly 16 m.m. long and 3 m.m. diameter, the current of ten told.

Leclanché cells does not in the least deflect the needle Solid vitreous selenium cannot, according to Berzelius,* of our highly sensitive galvanometer. Nor does light, so be rendered electrical by friction, but, on the contrary, far as our experiments have yet gone, diminish the resistBondsdorfft states that when rubbed in very dry air it ance of this modification. We have, on the other hand, has this property. I Knox found that fused selenium con succeeded in obtaining bars of granular selenium through ducted the current of a battery of sixty pairs. Hittorf which the current of one Leclanché cell causes a very found that granular selenium at normal temperatures con: considerable deflection of the needle. This forın is, we ducted sufficient of the current of one Grove's element to find, in its electric resistance almost unaffected by light. deflect the astatic needle of a galvanometer having 200 Between these two forms of granular selenium-lhe apconvolutions 17°, and that when the selenium was heated parently non-conducting and the comparatively highly to 210° in a small crucible the needle marked 80°. But conducting--there is another of intermediate resistance. when the temperature reached 217° (the point of fusion of This modification is highly sensitive to light; its congranular selenium), the needle went back suddenly to 20°. ductivity when i:1 the form of flat bars increasing in direct

The action of light as probably effecting some change sunlight 75 to 100 per cent, and in artificial light in ratios in the allotropy of selenium was not wholly unsuspected ranging from 10 to 50 per cent. prior to Mr. Smith's observations. Gmelin mentions ex One form of granular selenium, as Hiltof first showed, posure to sunlight as a favourable condition for the pre- has its resistance considerably diminished by heat: indeed, cipitation of selenium from dilute solutions of selenious he says that could it be heated red hot its conductivity acid by sulphurous acid; and Hittorf, while noting the would not be inferior to that of the metals. Our own exlikelihood of such an influence, was unable to detect it, periments confirm the diminution of conductivity by heat, and was obliged to attribute the observed change of amor- but we have found, in at least one modification which phous into crystalline selenium, while drying in sunlight, we have produced, a body which so far conforms to the entirely to the effect of heat. In pursuing the line of re metallic type as to have its resistance strikingly increased search we have marked out for ourselves, we have been by heat. We have made bars of selenium which when obliged to repeat much already published work, which placed in the circuit of a battery and galvanometer, have with improved means of experiment has lost somewhat of shown a deflection of 48°, while upon completing the cirits significance. We have thus encountered several ap- cuit of a nitric acid battery, the current of which heated parently contradictory statements, some of which our ex a spiral platinum wire surrounding the bar of selenium, perience has either failed to verify, or has placed in a new the needle gradually fell to 15°, as the temperature of the light; and we have been convinced that the properties of bar became greater. this remarkable substance are but imperfectly understood, For the present we refrain from comment upon these and still present a wide field for investigation. Vitreous results; and although we have been engaged during many selenium is, we should say at the outset, apparently an months in this investigation, we deser details of our exabsolute non-conductor of electricity. We have been un periments, and especially of the conditions under which able to obtain any deflection of the very sensitive astatic | the different electrically resisting and light-sensitive forms needle of a high resistance galvanometer, when the thin- of selenium are obtained, until with larger experience we nest films of selenium, of the continuity of which we may hope to bring before the Acadeiny results tending could assure ourselves, are interposed in the circuit of more closely to the solution of the questions we have proten Leclanché elements. The difficulty of producing posed to ourselves. very thin films of absolute continuity disposes us nevertheless to state our belief as to the complete non-conductivity of vitreous selenium with some reservation.

As might be expected from this character, selenium in ON PYROLOGY, OR ANALYSIS AND SYNTHESIS the vitreous form becomes electric by friction. So easily

BY MEANS OF THE BLOWPIPE.* indeed have we invariably obtained this result that we find it difficult to understand the contrary conclusion of

By W. A. ROSS. Berzelius.

(Continued from vol. xxxii., P. 254) Hittorf, as has been stated, sound that when vitreous selenium is converted into the granular form its electrical (7). It seems incredible, and yet is undoubtedly a fact, that resistance diminishes directly with its temperature, but that when 217° is attained the resistance is suddenly and

there are English chemists-accomplished ones too-and largely augmented. In repeating this experiment we have

even public analysts almost entirely ignorant of the obtained results concordant with those of Hittorf, who analytical use of the blowpipe. To foreigners, especially appears, however, not to have exceeded the temperature any systematic training, by means of lectures and practical

Germans, it seems strange that we have not in England ance diminishes up to the point of complete fusion of teaching, in blowpipe analysis, on the pattern of the the selenium, being at its maximum at 250°., We have be instituted by a rich Government like ours without

famous Freiberg University. Such a course might surely obtained also the remarkable result that when the vitreous much difficulty, in Jermyn Street, under the direction of selenium resulting from the rapid cooling of the completely sused granular form is quickly heated, it begins

one of the old Freiberg students, as, for instance, Her to conduct the current at a temperature between 165. and Majesty's Inspector of Mines, within whose superinten. 175°, and that its resistance diminishes, not only up to

dence the students might make periodical visits to the

most characteristic mines, which that gentleman knows * Gmelin, “ Handbook," ii., s. 236.

so well: so that this reproach may be taken from us. It + Gmelin, l.c. i Gmelin, 1.c.

* The term “ pyrological" ("pyrologischen Versuche ") has been $ Poggendorf, Annalen der Physik und Chimie, Bd. Ixxxiv., p. 214. adopted by Professor Richter, of Freiberg, in a letter to the writer.

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ON THE

CHEMICAL NEWS,
Development of the Chemical Arts.

3 Jan. 7, 1876.; is not a sufficient reply to say that "there is a course of be correct, to what may be termed the metaphysical blowpipe instruction in almost every English chemical chemistry of modern times, it seems insufficient when class or college." Every chemist who has been to Freiberg, absolutely and completely substituted for practical knowor even to the American colleges, knows how inefficiently ledge, and reasoning in mere English, and, indeed, it is the blowpipe is taught, or rather, how effectually it is obvious that, in England at least, there is a tendency neglected in our otherwise excellent schools of chemistry. among our best writers, even on chemical metaphysics, to If this point be controverted, it will not be difficult to express their thoughts, not only in English, but in the take one of our most generally received analytical text. very plainest English which has ever been in the possesbooks, and show what extraordinary and incorrect state sion of Her Majesty or her predecessors. There is no art ments there made with regard to blowpipe so difficult of attainment as simplicity, and we may safely analysis, nor does an inspection of some of the English regard the value of an invention (or the description of pyrological instruments and apparatus at all reassure us. one) in the inverse ratio to its complication. Whoever I have lately, incredible as it will seem, been shown an takés the trouble to compare the amazing hieroglyphical instrument as the only kind of blowpipe in use in a public work of the communistical chemist Nacquet, translated laboratory in London, having an aperture at the jet, at into English the other day, with the luminous essays least a quarter of an inch in diameter; and, to make of the marvellous apothecary Scheele ;t or Axiom V., Book matters worse, filled both with the blast and with aërated | I. of Newton's Optics, on the ratio between the sines of coal gas ! I saw a youth blowing through such a machine incidence and refraction in a ray of light, with the ordinary as this by means of a mouthpiece cleverly extemporised scientific account of the same simple law given in our with a glass funnel, and warned him that he would thus modern mathematical or physical works, will soon see probably injure his lungs, a misfortune which would of that the advantage in every essential particular remains course be attributed to the blowpipe," instead of to the with the adopters of expression by means of language. personal use of such a tuyere as this.

Besides, no one, ot even the most eminent philosopher, (8). It may be as well to mention here that blowpipes can afford to discard the very great advantage of address. like that devised by Von Frick, having the operator's ing himself to thousands-perhaps millions-of his fellow breath, or blast from any other source, and the gas for creatures, instead of to a few transcendentalists who ignition conveyed by the same tube, are utterly useless for cannot spread his opinions beyond their own clique. these purposes ; that Bunsen burners are useless for these purposes; that Fletcher's most ingenious, and no doubt otherwise invaluable “ hot blast blowpipe” is almost useless for these purposes, which are most erro

REPORT neously supposed to be always best effected by the greatest heat. Let any student who really wishes to learn this science produce a blue pyrocone from a candle by a hand

DEVELOPMENT OF THE CHEMICAL ARTS blower, and then with a mouth blowpipe held in the other

DURING THE LAST TEN YEARS. hand, direct a blast across this blue pyrocone, so as to

By Dr. A. W. HOFMANN. dissect it; he finds it to be a solid mass of blue Aame. If

(Continued from vol. xxxii., p. 286.) he now perform the same operation on the pyrocone from a gas jet, the pyrocone is found to be slightly hollow, while the pyrocone from a Bunsen burner has only the THENARD, on bringing peroxide of hydrogen into contact merest thin shell of circumscribing ignited gaseous

with his tongue, in order to ascertain its taste, found that matter. It is obvious, therefore, that the effect of holding it was whitened. The cuticle was also blackened, and at the fragment or paste of a mineral or other essay, in the the same time a violent itching was excited. Litmus paper middle of these three pyrocones, must be different in each without any previous reddening was at once decolourised, case; yet how seldom in England do we see a candle or

as was also turmeric paper. oil lamp used for important results which can be obtained

In 1863 Chevreuli undertook comparative experiments solely by its use?

on the bleaching power of hydrogen peroxide. Its con(9). It is obvious that in order to properly systematise centrated solution speedily turned syrup of violets green, the science of blowpipe analysis, we ought to reduce it to

oxygen being set at liberty. For the following experias close analogy as may be with the procedure in ordinary ments dilute colour-solutions were used—namely, syrup chemical analysis, which has been found to answer so

of violets, tincture of litmus, extract of peach-wood, and well. I have, therefore, in my method discarded the extract of logwood. The results were as follows:preliminary use of the salts borax and microcosmic sal, Time.

Violets. Litmus. Peach-wood. Logwood. and commenced attacking substances with the pyracids 10 mins. Imperceptible. Slight Change to " Boric and phosphoric anhydride.” Boric acid, indeed,

bleaching. contrary to the account found in most of our chemical

Complete Almost complete Turns, works, dissolves before the blowpipe no oxide whatever

bleaching

bleaching. yellow: completely, except those of the alkaline metals, and that 80 hrs... of silver a little, but its reactions thus are a thousand

Complete bleaching of all the solutions. times more valuable than if it really (as we are told) dis

Decolorisation is therefore effected less rapidly by persolved all those, while, by adding pyrologically a very

oxide of hydrogen than by chlorine. Tessié du Motay small proportion of alkali (not quite 5 per cent) we obtain

and Maréchaly mention it as one of the agents which they a still acid menstruum which is itself extremely soluble in propose for bleaching tissues, which, after treatment with water. Phosphoric acid, on the other hand, is, before the permanganate of potash, they recommend to be steeped blowpipe, the most powerful unmixed solvent in the in a solution of peroxide of hydrogen. But it had been world, dissolving gold leaf to a bluish violet glass quite much earlier applied as a bleaching-agent by Thénard? rapidly. In either case we can further, if we like, obtain himself for a particular purpose-namely, for restoring old an acidulated water solution, in which precipitates can be produced by alkalies, &c., just as in “the wet way," but

* The controversy at present proceeding between Dr. Frankland and

Mr. Wanklyn in the CHEMICAL News, with reference to water this process requires to be worked out, and shall not analysis, may be cited as an illustration of this point. therefore be further alluded to here.

+ Schetl: seems to have been a German, not a Swede, settled as a (10). It is necessary, however, to lightly t.uch upon

common apothecary, at Köping, in Sweden.

* “Berichte über die Entwickelung der Chemischen Industr one part of the subjeđ, not invidiously but conscientiously, Während des Letzten Jahrzehends." before proceeding to details. However invaluable the

Hi Chevreul, Comptes Rendus, lv., 733. application of the symbolical and algebraical process o.

S Bull. Soc. d'Encouragement, 1867, 472. Dingler, Polyt. Journal

cxxc(?)iv., 526. ratiocination may be, assuming its groundwork of facts to Pélouze and Frémy, Traité de Chimie, 1861.

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24 hrs...

Instrument for Measuring the Direct Heat of the Sun.

CHEMICAL News,

Jan. 7, 1876. oil-paintings and drawings. White-lead in old paintings, , many individual cases it may be far from being true. It which has become blackened by the gradual action of sul- would therefore seem to be desirable to get rid of this phuretted hydrogen, is converted into sulphate of lead by' uncertainty by constructing an instrument in which we dilute solutions of peroxide of hydrogen, and thus restored are sure that the causes of variability are not allowed to to its primitive colour. A fine drawing by Raffaelle, with operate. superimposed white which had become spotted with black, These causes of variability I have attempted to get rid of was completely cleansed by a solution which contained at in the following manner. With the help of Mr Jordan, most five or six times its volume of available oxygen, and mechanician at Owens College, the following instrument the paper did not suffer.

has been constructed. It consists of a large mercurial A peculiar, hitherto secret, application of this bleaching, thermometer with its bulb in the middle of a cubical cast. agent has been recently made public by A. v. Schrötter.* iron chamber, this chamber being of such massive material During the last few years bottles labelled “ Eau de Fon. that its temperature will remain sensibly constant for taine de Jouvence, golden," and containing about 140 c.c. some time. The chamber with its thermometer bas a of a colourless liquid, have been sold by perfumers in motion in azimuth round a vertical axis, A, and also a great cities. The price demanded is about 20 francs, and motion in altitude round a horizontal axis, B. A three to them, as it appears, is due that offensive člonde shade of inch lens, C, of 12 inches focal length is attached by means hair which holds an intermediate place between ash-grey of a rod to the cubical chamber so as to move with it. and bright yellow, and attracts the attention of tbe spec- The nature of this attachment will be seen in the figure. tators and the curiosity of observers by its piquante un Thus the whole instrument may be easily moved into naturalness. According to Schrötter this secret nostrum such a position that the lens as well as the upper side of is merely a solution of hydrogen peroxide made stable by the chamber which is parallel to the plane of the lens copious dilution, and by addition of a small quantity of may face the sun, and an image of the sun be thrown acid,-apparently nitric acid. According to Schrötter's through a hole, D, in the side of the chamber upon the careful examination it contained 6 volumes of available thermometer bulb, E. oxygen : 1000 grms. of the liquid would therefore contain 8.6 of available oxygen, or 18'3 of peroxide of hydrogen. As may be imagined, however, in case of an easily decom

с posable body, the bottles do not all contain solutions of equal strength. An examination conducted in the laboratory of the University of Berlin showed, in 1 volume of the solution, 94 to 9:8 vols. of available oxygen, corresponding to 136 grms. O, or 28.9 grms. H202, per litre. A bottle costing 20 francs yields the purchaser 2'5 to 4 grms. of this substance in solution, and effects its purpose completely, though slowly, within four to six days, thus strikingly illustrating the great efficacy of peroxide of hydrogen. The name of the perfumer who understands how to speculate so successfully upon the purses of his fair contemporaries, and who deserves to be known to posterity, is E. H. Thiellay, of London.

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ON AN INSTRUMENT FOR MEASURING THE

DIRECT HEAT OF THE SUN.
By Prof. BALFOUR STEWART, LL.D., F.R.S.

The instrument generally employed for giving the radiant energy of the sun's rays acts upon the following principle. In the first place the instrument is sheltered from the sun but exposed to the clear sky, say for five minutes ; let

The stem of the thermometer protrudes from the the heat so lost be termed r. Secondly, the instrument is chamber as in the figure. A screw, S, somewhat larger in turned to the sun for five minutes; let the heat so gained diameter than the bulb of the thermometer is made use of be termed R. Thirdly, the instrument being cow hotter

to attach the thermometer to its enclosure, and a smaller than it was in the first operation, is turned once more so as to be exposed to the clear sky for five minutes while it the thermometer to be properly adjusted and kept tight

screw, S', pressing home upon india-rubber washers enables is shielded from the sun ; let the heat so lost be termed r'. when in adjustment. It thus appears that r denotes the heat lost by convection and radiation united when the instrument, before being chamber is 2 inches, while the bulb of the thermometer is

In the present instrument the internal diameter of the heated by the sun, is exposed for five minutes to the clear about it inches in diameter. sky, while y denotes the heat lost by these same two

The scale of the thermometer is very open, more than operations by a similar exposure after the instrument has

an inch going to one degree. I have generally allowed been heated by the sun; and it is assumed that the heat the image of the sun given by the lens to heat the thermolost from these two causes during the time when the

meter bulb for one minute, during which time an increase instrument is being heated by the sun will be a mean between r and r', and hence that the whole effect of the has been produced.

of temperature, not exceeding in any case two degrees, sun's rays will be in reality

As far as principle is concerned there appears to be no 1+r.

objection to the present instrument, nevertheless it is open to a very serious practical objection. The scale

being so very open, the stem comprehends only a few Now although this assumption may in the average of a degrees ; srequently, therefore, the temperature is such great number of experiments represent the truth, yet in that the extremity of the mercurial column is either below

or above the stem. Now the thermometer has a small * Berl. Chem. Ces., 1874, 980.

A Paper read before the Manchester Literary and Philosophical upper chamber, and by means of a method of manipulaSociety.

tion well known to those who work with thermometers, it

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FROM THE

over

R+

CHEMICAL NEWS,

Analysis of Tell-Tale Sugar Liquor. Jan.7, 1876.

5 i s possible to add to or take away from the main body of is soluble in aminonia and absorbs readily free oxygen, it mercury in the bulb so as to keep the end of the mercurial is proposed to substitute it for the expensive pyrogallic column always in the stem. But experience has con acid now used in laboratories for the absorption of vinced me that for a thermometer with such a large bulb, oxygen. Pyrogallic acid must be very carefully preseived, frequent manipulation of this kind is not unattended with an account of the great avidity of this substance for danger to the bulb. On this account the instrument in oxygen, whilst cuprous oxide may be easily conserved in its present form is, I conceive, unsuited for steady work in a dry state and when necessary dissolved in ammonia. A an observatory from year to year.

solution of cuprous oxide in ammonia absorbing oxygen It is, however, possible without any appreciable sacrifice gas turns blue, owing to the formation of cupric oxide of the scientific principle of the instrument, to alter it in Cuo). The solution of cupric oxide obtained may be such a manner as to remedy this defect. Without altering again converted into a colourless solution of cuprous the size of the bulb, I should propose for a permanent oxide (Cu20) by placing in the liquor a clean copper wire. instrument a stem, say 18 inches long, with a bore of such | The formula CuO+Cu=Cu20 explains this reaction. diameter that the stem should embrace a range of temperature between 20° F. and 92° F. Thus somewhat less than 5° will go to the inch. The stem might be protected from the risk of accident by an appropriate shield. Let such a ANALYSIS OF “TELL-TALE SUGAR LIQUOR" thermometer be heated for two minutes and the size of the lens be somewhat increased. In this case a rise of

SAFES OF TWO VACUUM SUGAR PANS. something like 5° F. will be obtained, and this heating effe& might very easily be estimated to one-hundredth of

By G. C. STEWART, F.C.S., the whole, while the same thermometer would serve for Chemist at the Cappielow Sugar Refinery, near Greenock. all the temperatures likely to occur in these islands during the course of the year. I ought to add that a pasteboard cover gilded on the

All vacuum sugar pans (exceptional instances outside is made to surround the chamber, and also that looked) are furnished with “ tell-tale sugar liquor” sales between the lens and the chamber there is a pasteboard dentally or peradventure otherwise” boil over during

sugar liquor,” &c., which might accishield with a hole in it to permit the full rays from the the evaporating process in sugar refining, lens to pass-the object of this shield being to prevent rays from the sun or sky from reaching the instrument.

These safes yield, when emptied, solutions which may the thermometer before exposure to the sun will in all tion of the pans may have a great deal to do with this, as In such an instrument r or the change taking place in vary in chemical composition according to a great variety

of circumstances. First of all, the mechanical construcprobability completely disappear, while pe' will be ex

has also the position in which the safe itself is fixed. If tremely small. At any rate we may be quite certain that

the pan is low set and very short in the swan's neck, ten rtrol

to one but that the “liquor” drawn from the safe of such a pan will be found upon analysis to be much

richer in “sugar" and other organic matter than the will accurately represent the heating effect of the sun.

“liquor” drawn from another pan high set and very lofty We may probably suppose that in the same instrument in the swan's neck. the lens (which must always be kept clean) will always

Such is the case, and occasionally in sugar-boiling, when stop the same or nearly the same proportion of the solar

too much “salt " water is given to the condenser durrays. But the lens of one instrument may not stop the ing the evaporating process, it not unfrequently happens same proportion as that of another instrument. This, that this excess of salt water finds exit by “ more roai's however, is no objection if it be borne in mind that the

than down the Torricellian tube." instrument is a differential one. In practice there would When such an accident occurs, the “liquor" drawn be some standard instrument which would be retained at from the safe will be found upon analysis to be almost a central observatory, and all other instruments would,

“salt water," and will actually taste salt. before being issued, be compared with it. It would be By keeping up a continual examination of the thus possible to compare together the indications of “liquors ” drawn from these safes day after day, a various instruments working in different places provided good idea will be formed by the chemist in charge of that these, before being issued, had their co-efficients the sugar refinery as to how the pans are being handled determined at the central observatory.

by the pan-men.

The following two analyses of this “liquor" will be examined with curios ty by your numerous readers

who take a direct interest in the literature of the subLABORATORY NOTES.

ject. By SERGIUS KERN, St. Petersburg.

100 parts by weight contain :

Per cent. Per cent. (1). On a Reagent for Uranium.-With potassium ferro.

Crystallisable sugar

4.80

II'43 cyanide (K.FeCyó) a solution of a uranic salt yields a

Fruit sugar

3:37 4'52 brown precipitate of uranium ferrocyanide. The preci.

Extractive organic matter

1o76 I'5+ pitate obtained much resembles the precipitate of copper Insoluble matter

0:56

0:08 ferrocyanide, but may be distinguished by the solubility

Saluble salts..

2:57 0'90 of the precipitates in hydrochloric acid, viz., the uranium

Iron

0:26

0'45 ferrocyanide dissolves easily even in diluted hydrochloric

Copper

0'05 acid : the corresponding copper salt is insoluble in acids.

Water

86:47

81'03 This reaction may be used for the separation of copper from uranium. The uranium ferrocyanide dissolved in hydrochloric acid with a few drops of nitric acid gives a green colouration after being boiled for some minutes : No. 1. - This “sugar-liquor” is from the safe of a this reaction is proposed as a test for uranium salts. modern vacuum sugar-pan recently constructed, high in

(2). On the Use of Cuprous Oxide.—This compound is the swan's neck, and of artistic mechanical design. easily prepared by boiling a solution of copper sulphate No. 2.- Is the same liquor” drawn from the safe of with sugar and an excess of caustic potash. As the an old-fashioned vacuum sugar pan, low set, short in cuprous oxide (Cu20) obtained in the form of a red powder the swan's neck, and as old as Howard.

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No.1.

No. 2.

0:21

100'00

100'00

6
Sampling of Milk for Analysis.

CHEMICAL NEWS,

Jan. 7, 1876. NOTICES OF BOOKS.

needed by the crops, what must be the results of irrigation with sewage, carried on day by day? It must be

clearly understood that if we pour'any volatile liquid even Third Annual Report of the Board of Health of the City of upon the most perfect filter, evaporation takes place from

Boston. 1875. Boston: Rockwell and Churchill. the surface. If we keep the surface constantly moist, the This issue contains no small amount of important and evaporation is continuous, and if the liquid hold in solu. interesting matter. There is a paper on the ventilation tion any sewage gases these, too, must as by physical of schools by Dr. F. W. Draper, which takes up a subject necessity be delivered into the atmosphere. Between a hitherto neglected by sanitary reformers. Prof. W. R. sewage farm and a polluted river there is simply this dif. Nichols took samples of air in un school rooms and sub. ference, that the former exposes a far broader evaporating mitted them to analysis. The proportion of carbonic acid surface. The vicinity of a sewage farm may here and ranged from 3 volumes in 1000 to 0:57, with a general there, for a few years, appear healthy. But just the same average of 1:18. The greatest amount compatible with a may be said of certain places where the utmost sanitary healthy condition of the atmosphere is fixed by Professor neglect prevails. We could point out villages where the Pettenkofer at 0°7; the carbonic acid being regarded not only supply of water is either from shallow wells, separ. so much as a dangerous body per se, but as the measure of ated from cesspools by only a few yards of chalk and contamination in an occupied room as arising from organic gravel, or from roadside duck-ponds, receiving the drainproducts thrown off from the lungs and skin. It need age of cultivated lands and the oozings of farmyard dung scarcely be said that an apartment where the carbonic heaps. Yet the death-rate is low, and the inhabitants acid rises to 3 parts in 1000 is a most unfit place for healthy. Are we not from time to time informed of the children to spend some five or six hours daily. The means health and vigour of nightmen, scavengers, knackers, employed, often the only means provided, to remedy this bone-boilers, and others who are constantly engaged state of things is merely an additional evil. The windows among putrescent matter? Are their no hale old gentleare thrown open, and, as Dr. Draper puts it, “ the in men who have all their lives quaffed the waters of some evitable wave of cold outside air sweeps over the un. City pump, sparkling with carbonic acid due to decomcovered heads of the children and a fresh accession of posing animal substances, and whom no physician nor cases of bronchitis, or of more serious pulmonary affec. chemist can convince of its unhealthiness ? Such cases tions, is the result." In the inspection of the “Chapman as that of Norwood either prove nothing or a great deal school, a room showed at the desk-level a temperature of too much. If a sewage farm is healthy, sanitary reform 77°; three quarters-of-an-hour later the same room was is a needless luxury. revisited, when the thermometer indicated 6147, a fall of As to the “ astounding results ”—which are slow in 15'3. Between the two visits the teacher had aired'the taking the form of hard cash,—the " enormous crops," room to some purpose; the air was pure enough, and the and the “most luxuriant vegetation,” the eyes of the coughing and sneezing of the children gave warning that public are gradually being opened. At first we were told it was cold enough also. If such a sudden change should that sewage irrigation would render the application of occur in the outside atmosphere it would be considered manure superfluous; then it appeared that the dung of a fruitful cause of increased sickness in the community." | the stock kept upon the farm must be added; and now We greatly fear that were similar investigations under we find that the green crops are to be ploughed in to taken in England the results would be found not more enrich the soil ! Dr. Richardson exaggerates when he satisfactory than those given in the report before us. It says that precipitation processes allow all the soluble is at least certain that too many school-houses, instead matters in the sewage to escape with the effluent.

He of broad windows admitting those floods of light for which forgets, too, that of the combined nitrogen present in the children instinctively crave, are provided with narrow, sewage, a large part, varying from a quarter to two-thirds, mediæval loop-holes, calculated to admit only a dim goes off in the drainage from the irrigation farms. So mysterious light, symbolical of anything but intelligence, that precipitation and irrigation alike fail to secure all the and eminently calculated to make the pupils uneasy and valuable matter contained in sewage. That in India and fretful.

other hot, dry countries irrigation is often the one thing From the sanitary condition of schools we pass to a wanted to convert a desert into a garden, we fully admit. paper on the sewage question by Dr. W. L. Richardson, But in England, in average seasons, it is quite as clearly who appears to have swallowed the ex parte statements the one thing which is not wanted. of certain English irrigationists without the time-honoured The report further contains the yearly results of the grain of salt recommended on such occasions. Thus he chemical examination of articles of diet, medicines, &c., tells us that the existence of sewage farms, so far from as executed by the able chemist to the Board, Dr. W. R. being detrimental to the health of the vicinity, has actually Nichols. Special notice is given of a class of quack a beneficial effect. As proof of this statement-and in medicines largely sold under the name of bitters, but concidentally we must add, as a confirmation of the remark taining large proportions of alcohol, in one case as much that statistics can prove anything—he quotes from Dr. as 59 per cent. Corfield the case of Norwood, where, thanks to the establishment of a sewage farm, the mortality has fallen from 18 to 12'07 per 1000. Post hoc, ergo propter hoc ? “ This improved death-rate is of course to be attributed

CORRESPONDENCE. to the increased vegetation produced by sewage irrigation.” If luxuriant vegetation necessarily implies a low death-rate, what do we say to the Terai, the west coast of

SAMPLING OF MILK FOR ANALYSIS. Africa, the tierras calientes of Mexico, to rice-fields and mangrove swamps ? Admitting, for argument's sake, the

To the Editor of the Chemical News. Norwood case, we cannot overlook the facts detailed in Sir, -Since the Sale of Food and Drugs Act came into the official report on Progress of India, for 1871 and 1872, operation, I have observed on several occasions that the by C. R. Markham, C.B. Here it appears that the epi- mode of taking and dividing the samples of milk supplied demic of 1847 was more severe and more general in the to the analyst has an important influence on the comirrigated districts than elsewhere. A medical committee parative results of analyses made for the determination or of inspection recommended that irrigation should not be the fat. I am sometimes called upon to analyse not only brought within 200 yards of the villages, and that the the sample left vith me by the inspector, but also that atter should be screened by a double row of trees, left with the dealer, who is naturally anxious to know planted around the irrigated lands. If such are the effects the result quickly instead of remaining in suspense, it of irrigation with clean water, applied, moreover, only when may be, for weeks ; and I have not unfrequently found,

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