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water. The filtrate contains the Cs (or Rb) and the SO,, which are estimated as cesium chloroplatinate and barium sulphate. The insoluble residue, cobalt oxide, is heated in a hydrogen stream and weighed as metallic cobalt.

[blocks in formation]

c. Chromium Alums.—An experiment was tried using a solution of potassium chromate strongly acidified with sulphuric acid as electrolyte for the negative pole, and dilute sulphuric acid for the positive. After thirty-six hours no chrome alum was obtained, but considerable potassium sulphate was deposited, strongly colored green by the chromic solution present. On substituting ammonium chromate for the potassium chromate a considerable crop of chromium ammonium alum crystals was obtained at the negative pole. These crystals were very small. Four Bunsen cells were used in these experiments. This method of electrical reduction has been used by Piccini for the formation of vanadium' and titanium alums.

d. Experiments with Manganese.-These experiments were carried out in both the large and small apparatus; with manganese sulphate and ammonium, rubidium, and cesium sulphates; with varying quantities of free sulphuric acid in the electrolytes; with different strengths of current; and at various temperatures. The solution at the positive pole in every case became deep wine color, and the higher oxide of manganese was deposited. In one case only were a few minute octahedral crystals found in a rubidium manganese solution. These were deep wine color It is not, however,

and qualitatively contained manganese.

1 As COSO, after removal of Rb as Rb,PtCl ̧.

2 By loss at 200°.

2 By method described above.

4 Gazz. chim. ital. 25, [2], 451.

5 Ibid., 25, [2], 542.

improbable that these were crystals of common alum colored by manganese. In an experiment with ruthenium such crystals were obtained, the aluminum being probably derived from the porcelain diaphragm. In a number of cases the black precipitate at the positive pole, supposed to be manganese dioxide, when allowed to stand with concentrated sulphuric acid, showed itself under the microscope to be made up of flat, transparent, pale, wine-colored crystals, resembling elongated hexagonal plates. These are not readily soluble in water or acids. They were not further investigated.

The electrolytical method does not seem to be applicable to the formation of manganese alums from manganous salts.' It is hoped later to try the electrolytic reduction of manganates and permanganates.

e. Experiments with Ruthenium.-No crystallized oxy-salts of ruthenium are known. As the double salts of the trichloride crystallize well, an effort was made to obtain an alum by the electrolytic reduction of the nitrosochloride. The small apparatus was used. The solution at the negative pole was a solution

IV

of cesium ruthenium nitrosochloride, Cs,RuCI,NO, which had been boiled some time with sulphuric acid, and which might be supposed to contain the nitrososulphate. It was hoped to reduce the nitroso group and split it off as ammonia, leaving trivalent ruthenium in the presence of sulphuric acid and cesium sulphate, the most favorable condition for alum formation. No sign of alum was found, nor did the electrolyzed solution show reaction for trivalent ruthenium. A considerable quantity of ruthenium tetroxide, RuO,, was given off. This was probably owing to oxidation at the positive pole, some of the ruthenium solution having penetrated the diaphragm into the sulphuric acid which surrounded the positive pole. The formation of ruthenium tetroxide by electrolytic oxidation has not been pre

1 Since the above was in type, a further article by Piccini has appeared in the Zeitschrift für anorganische Chemie, 17, 361, describing the formation of the cesium manganese alum by electrolytic oxidation, in a method apparently like that described in this paper. No particulars regarding current, etc., are given. This would seemingly settle the question of the trivalence of manganese in manganic salts. Attention is called, as in our paper, to the advantage in using rubidium and cesium compounds where it is desired to obtain difficultly crystallizable compounds. Piccini's result renders it probable that the few octahedra obtained in our rubidium manganese experiment were really rubidium manganese alum; he also found his alum contaminated by aluminum from the diaphragm.

viously noticed.

Further experiments with other ruthenium

compounds are being carried on.

WASHINGTON AND LEE UNIV.,

July 1, 1898.

ON THE DETERMINATION OF UNDIGESTED FAT AND CASEIN IN INFANT FECES.'

BY HERMAN POOLE.

Received August 29, 1898.

L

AST summer I had the honor of presenting to the Society a paper on "Methods of Determining Fat and Casein in Feces."2 In that paper I mentioned the method I had adopted in the investigation I was then engaged in, and stated why the methods previously used did not give me satisfactory results. This paper may be considered as a sequel to that one, or perhaps more correctly, a résumé of the work I have done on the subject to this time. The methods given in the paper cited were used substantially as there given throughout all the cases, no better one having been suggested; in fact, my requests for other methods met with no response at all, showing that but little work had been done directly on this line.

The methods of analysis used may be briefly stated as follows: The feces were carefully removed from the containers as well as possible and thoroughly mixed, if practicable. A portion of

this was then weighed out and dried in an air-bath at 90° C. for one hour, and afterwards at 105° to 110° C. for two or three hours or until of constant weight. A portion of this dried residue was then treated with ether in a Soxhlet extraction apparatus to extract the fat and other substances soluble in ether. The extract so obtained was evaporated at 100° till dry and usually weighed. This weighing was not done in every case as it had no important bearing on the aim of the investigation, which concerned the undigested fat and casein only. After drying, the extract was saponified with alcoholic potash, a small portion generally remaining undissolved. Water was then added and the whole boiled till the alcohol had been expelled. Practically this was carried on until the mass was nearly dry, water having 1 Read at the Boston Meeting of the American Chemical Society, August, 1898. 2 This Journal, 19, 877.

been added during the boiling. The solution was then diluted with water and filtered.

The cholesterol being soluble in ether was then taken up by agitation in a separatory globe with that solvent. On allowing the mixture to rest the two liquids separated readily, especially after a reagitation. The treatment with ether was generally repeated once, occasionally twice. The second repetition was hardly necessary, as only traces were taken up.

The solution thus freed from cholesterol was evaporated nearly dry, dissolved with water, and the fat acid determined as usual by precipitation with mineral acid, collecting, and weighing. The solution was usually clear enough without filtration.

In many cases the cholesterol solution in ether was evaporated and that body determined. As this was only of minor interest and not germane to the investigation, it was done only when it did not interfere with other work. No regular ratio of the fat and cholesterol could be established.

The solid residue from the ether extraction was treated successively with water and alcohol and then dried at 100° C. This dried residue was afterwards digested in a mixture of equal parts of water and hydrochloric acid for some ten or twelve hours at a temperature of about 60° C. This dissolved the casein and at the same time decomposed the earthy fat acid compounds, and, on cooling, a collection of fat acid was always found. No attention was paid to this fat acid as, being in combination with bases, it was considered to have been digested or changed in the system, and only undigested fat was sought. This fat acid was quite hard and usually, though not always, nearly white in color.

After cooling the solution of casein and filtering, it was evaporated to dryness and the nitrogen determined by the Kjeldahl method. The casein was estimated as being 100 of the nitrogen so determined.

The results obtained are shown in the accompanying table, which contains the results from most of the cases examined:

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