298 
Milk. 
I. 
U. 
m. 
IV. 
Butter (pure fatty matters) 
Mineral matters (ash) 
74-46 
18-18 
2'69 
4-08 
0-59 
64-80 
25-40 
{'•»'} 
2-19 
56-50 
31-57 
(8-44) 
3-49 
61-67 
33-43 
2*62 
1-56 
0-72 
* Containiiig nitrogen .. 
100-00 
•43 
100-00 
100-00 
100-00 
•42 
Cream is lighter than milk, but slightly denser than pure 
water ; consequently it sinks in distilled water. No. 1 was 
skimmed off after standing for 15 hours, and was found to have a 
specific gravity of 1-0194 at 62^ Fahr. The specific gravity of 
two other samples of cream which stood 48 hours was 1-0127 at 
62" Fahr., and 1-0129 at 62° Fahr. Rich cream, I find, has a 
lower specific gravity than thin cream mixed with a good deal of 
milk, such as the sample analysed under No. 1. 
No. 2 may be taken as representing the composition of cream 
of average richness. It then contains about one-fourth its weight 
of pure butter. 
These differences in' the composition of cream fully explain 
the variable quantities of butter which are produced by a given 
bulk of cream. 
On an average, 1 quart of good cream yields from 13 to 15 
ounces of commercial butter. Occasionally cream is very rich 
in fatty matters, and then yields much more butter. Thus Mr. 
Horsfall states that a quart of cream in his dairy yielded 1 lb. of" 
butter, when the cows were out in grass, and no less than 22 to 
24 ounces of butter when the cows were fed in the house on 
rape-cake, bran, and other substances rich in oil. 
The cream which rises first I find is alwavs richer in butter 
than that which is thrown up later. Such differences are always 
particularly marked in warm weather. Generally spedking^ 
cream yields more butter when its bulk, in proportion to that of 
the milk from which it is taken, is small, and vice versa. Thus, 
in Mr. Horsfall's dairy, the cream did not. exceed 6^ per cent, in 
the bulk of the milk ; but it was so rich as to yield 25 ounces of 
butter per quart. * 
In an experiment which I published last 3 ear only 4 per cent, 
of cream was thrown up by the milk. This cream, however, 
was so rich that 10 quarts yielded 18 lbs. of butter. 
The first portions of cream which rise are always thin, but 
rich in fat ; a fact which is explained by the circumstance that 
during milking and the subsequent agitation to which milk is 
exposed a portion of the milk-globules get broken, in conse- 
