200 Report of tHe CHEMIST OF THE 
clear supernatant liquid. The preciptate is filtered, washed with 
water, and then, with the filter paper, treated by the Kjeldahl 
method to determine the amount of nitrogen. The nitrogen equals 
nitrogen present in the form of paranuclein (pseudonuclein). 
In our early work we used 2 or 3 cc. of a saturated alum solu- 
tion for this determination, for the reason that, in the separation 
of casein in milk, we had used this reagent successfully; but at 
the time we did not know the nature of the body we were pre- 
cipitating from our water-solution of cheese. Later, when we 
had studied it and learned its character, we found, on comparing 
precipitations by use of alum and by hydrochloric acid, that alum_ 
gave high results, undoubtedly precipitating some caseoses. In 
27 comparative trials with water-extracts of different cheeses, we 
found in the alum precipitate nitrogen varying from 0.2 to 0.837 
per ct. of the cheese and averaging 0.269 per ct., while the nitro- 
gen in the hydrochloric acid precipitate varied from 0.046 to 
0.145 per ct. of the cheese and averaged 0.085 per ct. The nitro- 
gen precipitated by alum in these 27 cases was from 2.1 to 5.5 
times as much as that precipitated by hydrochloric acid, the 
average of all being 8.2. Since hydrochloric acid is known to 
precipitate paranuclein completely, we are justified in assuming 
that the alum precipitates other compounds, and this is con- 
firmed by other work, showing that when alum is used as the 
first precipitant, we get smaller quantities of caseoses in the 
filtrate than we do when we use hydrochloric acid as the pre- 
cipitant of paranuclein. Alum appears to resemble zinc sul- 
phate as a precipitant of proteids. 
Paranuclein {pseudonuclein) results from the breaking down 
of casein or paracasein and is always found in the water-extracts 
of ripening cheese, whether salted or unsalted. It may, perhaps, 
be regarded more accurately as a residue, and probably should 
not be counted as one of the products to be used in measuring 
the extent of cheese-ripening. This is undoubtedly the same 
body as Chittenden’s dyspeptone,’ which he found as an insoluble 
residue in a pepsin-hydrochloric-acid digestion of casein. 
8Studies in Physiol. Chem. Yale Univ., 3: 66 (1887-8). 
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