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The table illustrates the method of writing the formulæ of bodies according to the types of water, hydrogen, and ammonia, to which they respectively belong. Determinations of the specific gravities of the vapor of water and of hydrogen show that the formulæ H O and H (0=S and H=1) agree to a condensation of two volumes. In order, therefore, to make types of these bodies, their formulæ must be doubled so as to correspond to a condensation of four volumes, which is the atomic volume of the greater part of organic compounds.
The formula for ammonia N H, already corresponds to four volumes, e. g., 2 vols. N +6 vols. H= 8 vols. condensed to 4 vols. N Hz.
It will be observed that, in the table, compounds of a basic character are placed to the left hand, those of acid nature to the right hand, while salt or neutral bodies occupy positions in the middle of the table.
It will be observed, further, that in the formulæ of the bodies according to the types + $02 and is the electro-negative elements are placed in the bracket to the left hand, and these are distinguished into a superior atom of hydrogen, capable of being replaced by chlorine, &c., or an acid radical, and an inferior atom of hydrogen susceptible of being exchanged for a metal or basic radical, while the electro-negative elements, oxygen, sulphur, &c., occupy positions to the right hand, outside of the bracket.
The relations existing between anhydrous or hydrated acids or bases; the difference between hydrogen acids and oxygen acids; the nature of acid, base, or salt, are more readily perceived by a close examination of the table than by the most extended description. It will be seen by this inspection how the ammonia salts are represented.
| 1 H,
Hly to the type ammonia we have a new type 1 N, ammonium, which enables
the formation of salts, according to the aminonium theory, by introducing this new type into the type of water. Thus diethyle-methyle-amylc-ammonium would be C. H: 7
C, H, 0, 7 C4 II; ? c .)
C, H, 7 ŞN. Its hydrated oxide C4 H, L > O2. Its acetate C4 II; } 02. C10 H11 )
C2 H2 ?
C1 Hu The homologous series may thus be generalized by this system of nomenclature—c.g., ordinary alcohol is c. 11, }O2; c. Hon }O2 is any alcohol, and
24 any corresponding acid of the same homologous series. Another principle, which has been adopted in the type method, consists in the assumption of radicals capable of replacing H, or H, in the types. Such radicals are diatomic when they replace H2, and are represented thus, (",) and triatomic ("'') when they replace Ilz; and the types of water, hydrogen, and ammonia are doubled or trebled to form new types by which bibasic or tribasic acids or salts may be represented. Thus :
The following are examples of the duplication and triplication of the hydrogen and ammonium types :
Type. Chloro-sulphuric acid. Chloride of succinyle.
C. H4 04"
C, H, Od")
Oxychloride of phosphorus.
HS These derived types are connected with the primary types by the hypothesis that a "polyatomic” radical may replace several atoms of hydrogen in the primary type. ThusType. Anhydrous sulphuric acid. Anhydrous succinic acid.
The following examples illustrate the use of the type method of expressing à chemical reaction-e. g., that of hydrochloric acid with hydrated oxide of ammonium. By the former method it would be
N H, O + HCl = H, Cl + H 0 By the type method
Again : by the action of oxychloride of phosphorus upon acetate of soda, chloride of acetyle is formed together with phosphate of soda, which reaction is represented. By the former method
P 0, Clz + 3 (N, 0, C, H, O3) = 3 N20, P 05 + 3 (C4 H, 02) Cl.
P 0," ka
. Na, so
CI. Some regard the type method of imagining a body as essential in the nature of matter; to these the type of the same body is invariable, with which, if
phenomena agree not, the reason is sought, and the correct type determined by experiment. But others employ this method as a means of comparing chemical reactions, and as suggestive of new experiments. Such write formulae sometimes according to the old nomenclature, and sometimes take great liberties with the types, viewing the same body in different types; for example, taking aldehyde
A very serious defect, in my opinion, in the type method is that it places the hydrogen acids and salts in a different type from the oxygen acids and salts; while the analogies existing between these acids and salts furnish urgent reason why they should have the same constitution, which similarity chemists have always labored to discover. It is not fair to constitute a type ammonia founded on the chemical analogies of it and the compound ammonias, and at the same time place hydro-chloric and nitric acids in different types. And yet, by the present method, they cannot come in the same type, because, first, oxygen can
not come in the hydrogen type, #} ; }} ; and second, in the water-type
#}o. the oxygen outside of the bracket is differently combined, compared with the oxygen of an oxy-radical replacing H. Thus nitrate of potassa must be N9. } O2, and not N96 } , (since O, and O2 are differently combined,) and
chloride of potassium can only be o In concluding the subject, it may be observed that by the former method of writing formulae, the binary nature of chemical compounds, owing to the polarity of their atoms, was kept prominent; while this is not the case with respect to type formulae, although in these the polarity of the atoms is not denied, but kept in subordinate view. Whatever be the faults or merits of the type method, it has, by placing bodies before us in a new relation, suggested experiments (which, perhaps, would not have been otherwise suggested) which have led to important discoveries. At the present time, not to understand this method of writing formulae is to be excluded from following the course of modern chemical progress.
RESEARCHES ON THE PHENOMENA
WHICH CHARACTERIZE AND ACCOMPANY
THE PROPAGATION OF ELECTRICITY
IN HIGHLY RAREFIED ELASTIC FLUIDS.*
BY PROFESSOR A. DE LA RIVE.
Translated for the Smithsonian Institution from the Memoires de la Société de Physique et
d'Historie Naturelle de Genede, tome XVII, 1863.
I was led in 1849, in my first memoir on the aurora borealis,t to show that the electric light which is produced in a vacuum of from four to five millimetres is obedient to the action of the magnet. I subsequently found that this experiment, in which, to produce electricity, I at first used an ordinary electric instrument, and then the hydro-electric machine of Armstrong, succeeded still better with Rubmkorff's induction apparatus. The employment of this apparatus has since supplied the means of studying in a surer and more commodious manner the propagation of electricity in rarefied gases, and thus the assurance has been obtained that, while an absolute vacuum will by no means transmit electricity, the presence in any space of the smallest quantity of ponderable matter in the state of an elastic fluid suffices for such propagation. To the conclusive experiments of M. Gassiot we essentially owe the demonstration of this important principle. It has been observed that the transmission of electricity through elastic fluids is effected with more or less facility, according to the nature and density of the fluid, and that it is accompanied, when the gas is very much rarefied, by an appearance which has been called the stratification of electric light, consisting in the phenomenon of a succession of strata alternately luminous and obscure, presented by the luminous electric discharge. The action of the magnet on this light has likewise been studied. M. Plucker, after numerous and important experiments, has ascertained its law in connecting it with the formation of magnetic curves. Lastly, different explanations have been offered of the stratification of electric light, some based on the peculiar mode of the production of electricity by Rubmkorff's apparatus, others referring it, not to the character of the apparatus producing the electricity, but rather to that of the medium which propagates it.
The phenomena just cited had awakened in me a lively interest, and I have for some years more particularly studied them. I have encountered great difficulties in this pursuit, as, on account of the necessity, in operating on highly rarefied elastic fluids, of having apparatus which will properly maintain a vacuum, as well as very delicate instruments to appreciate with minute exactness the degree of rarefacation. The establishment at Geneva, conducted by so skilful a machinist as M. Schwerd, has, however, enabled me in a great measure to
* For a table of French measures, compared with English, see the last page of this Report. + Annales de Chimie et de Physique, tome XXV, p. 310; and Comptes Rendus de l'Academie des Sciences, tome XXIX, p. 412.
surmount these difficulties, and to arrive at results which I can with confidence present to the society.
My earlier researches, which had chiefly for their object the study of the general phenomena, were directed only to hydrogen and nitrogen, two gases, differing greatly as regards their physical and chemical properties, and offering, moreover, the advantage of being at once simple, unalterable, and without action on the metals serving as electrodes. Atmospheric air, on which also I have often operated, acts very much as nitrogen, whether because the proportion of oxygen it contains is small in comparison with that of the nitrogen, or because this oxygen, at least in great part, quickly disappears by reason of the transmitted electricity, which, converting it into ozone, facilitates its combination with the metal of the electrodes. I have also, in some cases, mixed with the gas submitted to experiment a little vapor of water or of alcohol.
Electricity has, in my experiments, been produced by a Rubmkorff induction apparatus of mean force, set in action by one or two pairs of Grove's cups,* and operating by means of the ordinary cut-off. The electricity thus produced is transmitted by means of copper wires covered with gutta-percha through the gaseous mediums, more or less rarefied, contained in glass vessels of different forms, tubes, jars, spherical or ovoid globes, &c. These vessels are to be carefully closed with good taps, and furnished with metallic electrodes of divers forms and natures, which serve to introduce the electric currents. † In the circuit which these currents are destined to traverse we place distilled water in a small glass trough, some twenty centimetres in length by five in width and three in depth. Two plates of platina fixed respectively at the extremities of the trough, and whose surface is exactly equal to the transverse section of the stratum of water, serve to establish this water in the circuit. The purpose of the interposition of the water is to determine the intensity of the electric current by means of an expedient which permits, with that view, the employment of a very delicate galvanometer. Two wires of platina, each inserted in a glass tube, are attached vertically to solid supports, so as to be immersed in distilled water at their lower extremities, which extremities project from the glass only a milli
* The battery in question is but a particular form which I have given to Grove's apparatus to render its management more convenient and prompt. It is constructed as foilows:
A glass jar with a large opening of about ten centimetres, closed with a glass stopper rubbed with emery, contains about a litre of nitric acid. When the pair is to be used, we remove the stopper and replace it by a porous cylinder of such diameter that it can enter freely into the jar by the opening. This cylinder, long enough to be plunged nearly to the bottom of the jar, has on its upper portion an annular protuberance, by means of which it rests on the edge of the opening. “It contains sulphuric acid diluted with water, and a tube or strip of zinc immersed in the acid solution. It is, besides, surrounded externally with a thin plate of platina, to which is soldered with gold a wire, also of platina, which terminates outside, traversing the annular projection of the porous cylinder.“ The zinc and the platina wire each carry nippers, by which the conductors are readily attached. There may be several similar pairs, and nothing is easier than to arrange them in series, so as to obtain a battery more or less powerful. But a single pair is sufficient, if well mounted, for nearly all electro-dynamic experiments, and particularly for the demonstration of the laws of Ampére, as well as for the production of the phenoinena attending the discharge of the Rulmkorff apparatus in rarefied gases.
It is not necessary often to change the nitric acid, since the jar contains a large quantity. The same acid may serve for several days and for many experiments. It is of advantage, however, frequently to change the acidulated water which fills the porous tube-a very easy and unexpensive operation. Finally, an important precaution to be taken is, that, when we cease to use the pair, the porous cylinder should be withdrawn from the nitric acid, care being taken immediately to replace it with the stopper rubbed with emery, and the cylinder should be immersed in a bottle filled with pure water. Thus the emanations of the nitrous vapors, and the penetration of the nitric acid through the porous cylinder, are avoided. We should guard against immersing the amalgamated zincs in the same water in which the porou : cylinders have been plunged, for the smallest trace of nitric acid in water suffices to alter the zincs.
For electrodes I have chiefly used balls of platina, one centimetre in diameter.