Primary Cleavage Products. 377 
phorus, the alkaline fluid was acidified with nitric acid, evaporated 
to dryness, the residue dissolved in a little water acidified with nitric 
acid, filtered, and the phosphoric acid precipitated in the usual man- 
ner with ammonium molybdate. After standing 24 hours at 40° C. 
this precipitate was filtered off, dissolved in ammonium hydroxide 
and the phosphoric acid re-precipitated as ammonio magnesium phos- 
phate and ultimately weighed as magnesium pyrophosphate. The 
accompanying tables show the results of the analyses of the different 
samples of casein. 
Comparing now the average composition of these different prepa- 
rations of casein, it is to be seen that they all show a very close 
agreement throughout. Thus the percentage of phosphorus in the 
seven preparations varies only from 0°84 to 0°89, sulphur from 0°75 
to 0°89, nitrogen from 15°75 to 16°08, hydrogen from 7:01 to 7:11 and 
carbon from 53°19 to 53°53 ; or leaving out one preparation which for 
some reason showed a high content of carbon, from 53°19 to 53°39 
per cent. The results therefore show a constancy in composition 
fully as marked as observed by Hammarsten and thus tend to confirm 
the latter in the view that casein is a single body of definite com- 
position. : 
Comparing our results collectively, with those obtained by Ham- 
marsten (see table showing average composition), we find a fairly 
close agreement throughout, although minor differences are tobe 
observed. First, all of our preparations show a content of carbon 
somewhat higher than found by Hammarsten. The latter investiga- 
tor found the carbon in bis preparations to vary from 52°78 to 53-09 
per cent., while in all of our preparations, the content of carbon cal- 
culated to the ash-free substance is above 53 per cent. The possi- 
bility of our preparations still containing some fat was rendered 
improbable by the thorough treatment with ether which they had 
received, and further by the fact that the nitrogen in our preparations 
was also somewhat higher than found by Hammarsten. One of the 
preparations, however, with a high content of carbon, was extracted 
again for several hours with boiling ether, but on analysis the con- 
tent of carbon was found unchanged. ‘The content of phosphorus 
agrees exactly with Hammarsten’s results, while the sulphur is, on an 
average, 0°] per cent. higher. There is nothing in the content of sul- 
phur, therefore, to even suggest confirmation of Danilewsky’s views. 
The amount of ash in our preparations was somewhat larger than 
found by Hammarsten and further, there is no especial connection to 
be seen between the content of ash and the precipitant used; the 
Trans. Conn. AcApD.. Vou. VII. 48 Nov., 1886. 
