breast to feed the suckling babe that was perchance to become an editor and a leader of men. The editor may be a great man and a moulder of public opinion but he is not as important to the human race as the old cow. The dairy business is the only one to which you should give free advertising.

Fellow editors let us stand by the honest cow, and verily we shall have an abundance of cash subscribers, genuine butter for our bread, milk for our babies-and the earth and the fullness thereof shall be ours.

THE DETECTION OF FORMIC ACID IN FRUIT PRODUCTS.

BY F. L. SHANNON.

In Bulletin No. 195, of the Dairy and Food Department of the State of Michigan, the author called attention to the fact that formic acid was being used in this country as a preservative of fruit products.

It has been the general belief among chemists for some time, that some preservatives other than the ones ordinarily found were being used in the preservation of fruit products and investigations have been made in various laboratories throughout the country for the purpose of determining the identity of the substance used. Owing to its use in Germany a number have suspected formic acid and have built up their investigations with that substance in mind, but because of unsatisfactory and indirect methods of identification and further owing to the fact that many substances respond to these indirect methods, it has been difficult to reach a positive conclusion.

A search of the literature on the subject revealed the fact that the detection of formic acid did not depend upon its isolation and subsequent identification, but mainly upon the indirect method of its reducing power, principally upon silver nitrate and mercuric chloride solution. For example, the older literature states that formic acid is a constant constituent of many plant and animal products, a statement based on the fact that when they are subjected to steam distillation some substance is obtained in the distilate which reduces silver nitrate and mercuric chloride solution. However, in view of recent investigations along this line, it seems that this whole subject of the natural occurrence of formic acid needs further study, as it has been found possible to subject a host of substances which were known to contain no formic acid to steam distillation and obtain a distillate which gave a pronounced reduction with both silver nitrate and mercuric chloride solution. From none of these substances however has it been possible to isolate and identify formic acid as such. Therefore, it is evident that we are not justified in designating as formic acid every substance obtained by steam distillation which reduces silver nitrate and mercuric chloride solution. It was found, for example, that when phosphoric acid was subjected to distillation the distillate possessed the reducing properties generally ascribed to formic acid. Furthermore, in a number of methods in which the formic acid recovered by steam distillation is neutralized using

phenolphtalein as indicator, the indicator itself was found to have a reducing action on mercuric chloride.

One of the most satisfactory indirect methods for the detection of formic acid is based on its reduction to formaldehyde by means of magnesium and dilute sulphuric acid. Fenton has shown that carbonic acid may be reduced in the same way, but Bacon has called attention to the fact that this is of theoretical importance only, there being no danger of confusing the two in practice. However every step in this method must be carried out with absolute precision, or erroneous conclusions may be drawn.

The qualitative method as applied to the products used in this investigation is as follows: To about 200-500 cc. of the syrup or crushed fruit . in a two litre, long necked, round bottom flask provided with a Reitmeier bulb, add about 50-100 cc. of water. Subject to steam distillation, collecting the distillate usually about 2500 cc. until it ceases to give an acid reaction with litmus.

Exactly neutralize the distillate with N/1 NaOH using litmus as an indicator. Evaporate on a steam or water bath to about 50 cc., transferring from the large evaporating dish to smaller ones as the volume decreases. Transfer to an Erlenmeyer flask, provided with a glass tube about three feet long as an air condenser, add a few pieces of pure magnesium ribbon or wire and a slight excess of dilute sulphuric acid and set in a cool place for one hour, adding dilute sulphuric acid through the tube from time to time as the reaction ceases. Transfer the liquid to a suitable distilling flask and collect the first ten cc. of the distillate, which will contain most of the formaldehyde, if the original syrup contained formic acid.

There are a number of methods published for the detection of formaldehyde and nearly every analyst has his favorite test. However, the methods which proved the most satisfactory in this work were, Leach's method,1 Phloroglucinol method, Rimini's method, and the Rescorcin method of the United States Pharmacopoeia. A positive reaction with these four tests was considered exclusive evidence of the presence of formaldehyde.

CRYSTALLOGRAPHIC IDENTIFICATION.

In as much as practically all methods for the detection of formic acid previously reported are indirect methods depending upon the decomposition of the formic acid or upon its reducing powers, it seemed desirable to attempt the isolation of formic acid in the form of an insoluble salt. The usual procedure in determining the identity of an organic acid in plants is to prepare some readily crystallizable salt, sparingly soluble in water. Of the various formates the lead salt crystallizes readily without water of crystallization, is very stable and requires 63 parts of water for solution. The formation and identification of lead formate would therefore constitute a direct and positive proof of the presence of a formic acid. After numerous attempts the following proceedure was adopted:

Steam distill about 1000-1200 cc. of the syrup as in the first operation, collecting the distillate (2500-3000 cc. in a receiving flask to which about 5 cc. of lead cream has been added.) (This is made as follows: Precipitate a solution of lead nitrate with potassium or sodiumhydrate in the presence of phenolphthalein until a faint pink color appears. Wash by decantation 8-10 times.) Shake the flask occasionally and as the lead hydrate is dissolved add a few cc. more, until all of the formic acid is combined. Concentrate the liquid in a large dish on a steam or water bath to about 50 cc. Filter and transfer to a suitable crystallizing dish and set aside in a desiccator. If formic acid was present in the original material needle like crystals of lead formate will form. Wash the crystals with absolute alcohol, to remove any lead acetate which may be present, spread on filter paper and dry. To the dry crystals apply the following tests:

Aqueous solution will reduce Ag No3 upon warming.

(b) Aqueous solution will reduce mercurie chloride solution upon warming.

(c) Aqueous solution will reduce platinum chloride upon warming. (d) To a portion of the crystals in a dry test tube add Sulphuric acid and warm. Carbon monoxide is generated which will burn in the tube with a blue flame when ignited. Further note that the lead formate is not discolored.

Transfer some of the crystals to a small distilling flask, treat with conc. phosphoric acid and distill. The distillate which is formie acid will react as follows:

1. Acid to litmus and acid taste.

2. Reduces silver nitrate on warming.

3. Reduces mercuric chloride on warming.
Reduces platinum chloride on warming.

5. Is reduced to formaldehyde by magnesium and dilute sulphuric
acid.

As previously mentioned it was found that when phosphoric acid and water alone were distilled the distillate would reduce silver nitrate and mercuric chloride solution. Therefore, before test (e) was carried out the phosphoric acid was subjected to distillation until it no longer gave a distillate that would reduce silver nitrate or mercuric chloride. The crystals of the lead compound were then added and the distillation continued.

Although the chemical evidence that the volatile acid obtained from the fruit products used in this investigation is conclusive, it thought desirable to submit the crystals to Dr. Edward H. Kraus, Professor of Geology and Minerology, University of Michigan, and he reports as follows:

"The crystals which were examined crystallographically, were ob tained by slow crystallization from an aqueous solution of the material furnished by Fern L. Shannon, State Analyst, Lansing, Michigan. They are prismatic in habit and about 2 to 3mm. in length and of slightly yellowish color. All crystals were clear and transparent. Although the crystals were in general doubly terminated, readings were made only upon the faces of the prism zone, the end faces being extremely

small and, hence difficult of adjustment. The images obtained were very good considering the size of the crystals.

The measured angles, compared with the values given by Plathan for are as follows:

mm (110) : (110) 73°

Kraus.

26' 73°

Plathan.
28'

mb (110) : (010) 53° 17% 53 16'

This comparison shows that the agreement in the values for this material and those given by Plathan' for lead formate are exceedingly close.

Parallel extinction was observed upon all the faces examined. The indeces of refraction are higher than that of methyleze iodide, as determined by the Becks and the Schrodder van der Kolk methods.

The above crystallographic-optical properties, together with the fact that a distinct reaction for lead is easily obtained upon the plaster tablet with the blowpipe, indicates conclusively that the substance examined is lead formate."

To further substantiate the proof a number of fruit syrups that were known to contain no added formic acid were subjected to steam distillation and an attempt made to separate a lead compound. In some instances a few crystals were obtained, but at no time could the crystals give the characteristic tests for lead formate.

It would seem then that the formation of formaldehyde coupled with the formation of lead formate and their subsequent identification would furnish a conclusive and positive proof of the presence of formic acid. The author desires to take this opportunity to thank Dr. Edward H. Kraus for his cooperation in this work.

MICHIGAN DAIRY AND FOOD DEPARTMENT.

March 19th, 1912.

DAIRY MEETINGS.

During the year sixty educational dairy meetings have been held in the state at the following places: Cadillac, Traverse City, Elk Rapids, East Jordan, Muskegon, Orleans, Lawrence, Lapeer, Shelby, Detroit. Kalamazoo, Imlay City, Port Huron, Alpena, Lake City, Millersburg, Onaway, Towar, Indian River, Wolverine, Vanderbilt, Gaylord, Frederick, Roscommon, St. Helen, West Branch, Alger, Sterling, Standish, Pinconning, Gladwin, Linwood, Kawkawlin, Fosters, Burt, Montrose, Flushing, Lennon, Carland, Elsie, Ashley, North Star, Ithaca, Traverse City, Alma, Forest Hill, Shepherd, Rosebush, Mount Pleasant, Clare, Farwell, Lake George, Temple, Marion, McBain, Boon, Harrietta, Mesick, Pomona, and Copemish.

All were addressed by the Deputy Commissioner who reports a growing interest in intelligent and scientific dairy work throughout the state. 1 Grothe, Chemische Krystallographic, 1910, 3. 16.