Primary Cleavage,Products. 369 
tion with oxygen in an open tube, the gases passing over a long layer 
of granular oxide of copper at a bright red heat, a layer of lead chro- 
mate at a dull red heat and a roll of freshly reduced metallic copper. 
Nitrogen was determined as nitrogen gas by combustion with oxide 
of copper, the gases passing over a long anterior layer of heated 
oxide, a short layer of metallic copper and a final layer of oxide of 
copper. The tube was exhausted with a Sprengel pump before and 
after the combustion and the nitrogen was collected in a Schiffs’ azo- 
. tometer, provided with a jacket tube for rapid cooling of the gas toa 
constant temperature. In the determination of sulphur and phospho- 
rus, the substance was fused with a mixture of potassium hydroxide 
and potassium nitrate (10 grams of the former and 1°5 grams of the 
latter) in a silver crucible, according to the method designated by 
Hammarsten * as 1a. In order to economize time, a single fusion was 
made to serve for both a sulphur and phosphorus determination ; in 
other words, a sufficient amount of casein (usually 1:2 grams) was 
fused with potassium hydroxide and nitrate, the fused mass dis- 
solved in water, the solution made up to a known volume and then 
one-half, representing one-half of the original substance, was used for 
the sulphur, the other half for the phosphorus determination. Both 
the alkali and the nitrate were free from sulphur and phosphorus; at 
least to such an extent that in a blank experiment, the resultant 
solutions gave no precipitate whatever, with either barium chloride 
or with molybdic solution. The oxidations were made at as low a 
temperature as possible, except towards the end when the temperature 
was raised, and occasionally a little more nitrate added, to facilitate 
complete oxidation. 
As the percentage of sulphur was quite an important point, we 
took particular pains to have the final acid fluid entirely free from 
nitrate and nitrite, as well as from any excess of hydrochloric acid, 
so as to avoid as much as possible any solvent action on the 
barium sulphate. For the determination of sulphur, therefore, the 
alkaline solution of the fused mass was acidified distinctly with hy- 
drochloric acid and the acid solution evaporated to perfect dryness 
on the water-bath. In this way the objectionable nitrate and nitrite 
were removed. The residue was then moistened with hydrochloric 
acid, taken up in water, and the solution allowed to stand until any 
chloride of silver present, had settled out. The fluid was then fil- 
tered and precipitated as usual with barium chloride. For phos- 
* Zeitschrift fir physiologische Chemie, Band ix, p. 289. 
TRANS. Conn. ACAD., Vou. VII. 47 Nov., 1886. 
