fat-free human hair, and digested it with 6 1. of 2 percent sol. of potassium permanganate. The mixture was allowed to stand for several days, with occasional shaking. The clear fluid was filtered, and the filtrate acidified with hydrochloric acid. The resulting precipitate was washed, first by decantation and then on a filter, redissolved in dilute soda sol. and precipitated by acidification. The precipitate was thoroughly washed, and dried, first in the air, then in an air-bath at 110° C. The dry substance was weighed and analyzed in the manner described above.

II. 1.3399 gm. of the substance gave 0.1407 gm. of barium sulfate (0.01933 gm. of sulfur).

III. 0.1900 gm. yielded 0.1980 gm. of barium sulfate (0.00272 gm. of sulphur).

The substance contained, therefore, judging from the results of the two analyses, 1.44 percent and 1.43 percent of sulfur, respectively. The oxy-proto sulfonic acid from egg-white contains, according to Maly,2 1.77 percent of sulfur. Since only a small amount of oxy-proto sulfonic acid resulted from the oxidation of the hair, it is clear that only a small part of the sulfur of the keratin remained in the oxy-proto sulfonic acid.

In order to determine how much sulfur is held in the solution as sulfuric acid, and how much is held in the form of some organic combination, after oxidation by permanganate, I have carried out two parallel experiments on the products of the oxidation.

In the first experiment, 9.2160 gm. of dry, fat-free hair were digested in 700 c.c. of 2 percent sol. of potassium permanganate. fter four days the liquid over the hair was perfectly clear. It Was filtered, and from it two portions of 100 c.c. each were taken (IV-V).

IV. The first portion was evaporated to dryness, treated with dilute hydrochloric acid, and the resultant precipitate of oxy-proto sulfonic acid was repeatedly extracted with water; the filtrate, together with the wash-water, was evaporated, and precipitated with barium chlorid. It yielded 0.040 gm. of barium sulfate (0.0055 gm. of sulfur). Therefore, in the 700 c.c., 0.0385 gm. of sulfur was held as sulfuric acid.

2 Maly: Monatsch. f. Chemie, 1884, viii, p. 255.

V. The second portion of the same fluid was evaporated to dry

ness, and the sulfur-content determined, after fusion with potassium hydroxid and potassium nitrate. The result was: 0.5172 gm. of barium sulfate (0.07105 gm. of sulfur). Hence, the sulfur-content of 700 c.c. was 0.4974 gm. It is clear that a much greater amount of the sulfur (92.3 percent) is contained in the filtrate from the oxy-proto sulfonic acid in the form of some organic combination, and only a small part (7.7 percent) is present in the solution as sulfuric acid.

For the second experiment, 10.2085 gm. of dry fat-free human hair were digested with 800 c.c. of 2 percent sol. of potassium permanganate and allowed to stand for 3-4 days, until the fluid was perfectly clear. This was then filtered and, of the filtrate, two portions of 100 c.c. were taken.

VI. The first portion was treated as in determination IV, with the difference, that this time the sulfur-content of the oxy-proto sulfonic acid precipitate was also determined. The filtrate and wash-water were treated with barium chlorid after the removal of the oxy-proto sulfonic acid, and yielded 0.4230 gm. of barium sulfate (0.005811 gm. of sulfur). Hence, in 800 c.c., 0.0465 gm. of sulfur was present as sulfuric acid.

VII. After the fusion of the oxy-proto sulfonic acid precipitates, with a mixture of potassium hydroxid and potassium nitrate, 0.0117 gm. of barium sulfate (0.00161 gm. of sulfur) was found. The sulfur in the oxy-proto sulfonic acid amounted, therefore, to 0.0129 gm.

VIII. The second portion was treated as in determination V. After fusion, 0.4694 gm. of barium sulfate (0.06449 gm. of sulfur) was obtained. Hence, 0.5159 gm. of sulfur was present in 800 c.c.

From these experiments it follows, unquestionably, that the greater part of the sulfur occurs, after oxidation with permanganate, as water-soluble organic substance. Of the total sulfur-content in the dissolved oxidation products (0.5159 gm. of sulfur) there were found: 9 percent as sulfuric acid, 2.5 percent as oxyproto sulfonic acid, and 88.5 percent as a water-soluble organic substance.

This water-soluble substance gives a precipitate with lead acetate, dissolves slightly in dilute alcohol, and is almost insoluble in 95 percent alcohol. I have used the following method, based on these properties, for the isolation of this substance: 70 gm. of hair were digested with 5-6 1. of 2 percent potassium permanganate sol. and allowed to stand for several days. The clear fluid was filtered, acidified with hydrochloric acid, and the precipitate separated by filtration. The filtrate was made slightly alkalin with dilute soda sol., and precipitated with lead acetate. The precipitate was washed, first by decantation and then on a filter, suspended in water, and treated with hydrogen sulfid. Precipitated lead sulfid was removed by filtration, the filtrate evaporated to a syrupy consistence, and extracted several times with 95 per cent alcohol. The residue was dissolved in a small amount of water, and the solution yielded a precipitate with a large excess of alcohol. This precipitate was dissolved in a little water and re-precipitated with alcohol. The final Product contained 12.5 percent of ash and 8.81 percent of sulfur. In order to purify the product it was re-dissolved several times in water, re-precipitated with alcohol, and washed with alcohol and ether. This purified material was dried at 110° and analyzed (IX-XVI).

IX. 0.1437 gm. gave, after ignition, 0.0089 gm. of ash, which consisted of silicic acid, with traces of potassium, sodium, calcium, iron and manganese.

X. 0.0743 gm. gave, after ignition, 0.0046 gm. of ash. XI. 0.1881 gm. gave, after burning with lead chromate, 0.2537 gm. of carbon dioxid and 0.0928 gm. of water.

XII. 0.1808 gm. burnt with lead chromate, yielded 0.2385 gm. Of carbon dioxid and 0.0908 gm. of water.

XIII. 0.2166 gm. gave 26.3 c.c. of nitrogen, at 23.5° and 763 mm. Hg.

XIV. 0.1762 gm. gave 21.1 c.c. of nitrogen, at 22.5° and 762 mm. Hg.

XV. 0.1578 gm. gave, on fusion by the method described above (determination I), 0.1121 gm. of barium sulfate.

XVI. 0.1787 gm. gave 0.1247 gm. barium sulfate.

The substance so obtained is acid in reaction, is very hygroscopic, and gives, with lead acetate, a precipitate which is soluble in an excess of the reagent, and in lead acetate sol. The substance gives the biuret reaction. Its aqueous solution gives, on treatment with alcohol, a milky turbidity which, on evaporation, deposits small crystals. The material is very stable and, on heating with mineral acids, is decomposed with the formation of sulfuric acid. To determine its basicity the aqueous sol. was titrated with 0.0983/N soda sol., with lacmoid-naphthol-green as the indicator.

XVII. 1.3 c.c. of the soda sol. was required to neutralize 0.1053 gm. of the substance dissolved in water. For a monobasic acid (C10H17N3SO6) 3, 1.2 c.c. would be necessary, but it must be considered that the ash of the substance contained a large amount of silicic acid.

B. In order to ascertain the sulfur-distribution among the oxidation products of cystin, I have oxidized, with potassium permanganate, cystin prepared from human hair. About 2.3 gm. of cystin, containing 0.61 gm. of sulfur, were oxidized with I 1. of permanganate sol. All of the filtrate, together with the washings, was evaporated and the contained sulfuric acid determined (XVIII).

XVIII. I obtained 2.0931 gm. of barium sulfate (0.2875 gm. of sulfur). Therefore, 47 percent of the total sulfur was changed to sulfuric acid in the oxidation.

To 40 c.c. of the filtrate, which was obtained in the oxidation of the hair with 2 percent potassium permanganate sol. (p. 19) and which contained 0.0022 gm. of sulfur as sulfuric acid, was added 0.2300 gm. of cystin (with a sulfur-content of 0.0614 gm.), and 4550 c.c. of 2 percent permanganate sol. After the reaction was ended, the fluid was filtered, the precipitate washed and the filtrate together with the washings was evaporated to dryness. The residue was acidified with hydrochloric acid, and the precipitate of oxy-proto sulfonic acid separated by filtration. The new filtrate, with the washings, was then precipitated with barium chlorid in the usual way (XIX).

XIX. From this precipitate 0.2266 gm. of barium sulfate (0.0311 gm. of sulfur) was obtained. Thus, from the oxidation of cystin I obtained 0.0311-0.0022, 0.0289 gm. of sulfur, or 46.9 percent of the total sulfur, as sulfuric acid.

From the results of these experiments it follows that a much larger amount of sulfur is split off as sulfuric acid by the oxidation of cystin with permanganate than by the similar oxidation of keratin. It is further to be noted that, in the process, some cystin always remains unoxidized and that, among the oxidation products of cystin, a small amount of hydrogen sulfid is always present, while in the distillates of the oxidation products of hair, hydrogen sulfid is never found.

General conclusions. These data suggest the following conclusions: In the oxidation of keratin the largest part of the contained sulfur remains in organic combination, and only one tenth is converted into sulfuric acid. The oxidations of cystin and of keratin proceed along different lines.

I have undertaken further work on this subject.