268 Original Articles, | April, 
adopt means to ensure, as far as possible, that we obtain our money’s 
worth. Professing, as we do, a decided preference for the healthy 
and natural fluid, over any artificial representation of it, however 
superior in the estimation of the vendor, we call in the aid of 
science, to inform us what we ought to have, even if it gives us, 
at the same time, the miserable satisfaction of knowing that we have 
it not. 
General Composition and Characters of Milk.— Milk is the secre- 
tion derived from the blood supplied to the mammary gland of the 
female animal, of the class mammalia. It is never produced im any 
quantity until after parturition; but during the latter part of utero- 
gestation it occurs In appreciable amounts, and instances are on record 
where it has been obtained from the gland of an animal previous to 
impregnation. The fluid secreted before parturition, and for some 
time afterwards, is called Colostrum, and contains a number of large 
corpuscules, filled with oil globules, distinguished as the ‘“ Colostrum 
Corpuscules.” 
Milk is white in colour, opaque, and has an agreeable sweetish 
taste ; the odour is faint, but peculiar. 
Its density is greater than that of water. Cows’ milk, of good 
quality, has a specific gravity of about 1030; human milk 1020; 
Goats’ and ewes’ milk 1035 to 1042, and asses’ milk 1019, compared 
with water at 1000. 
The chemical reaction seems to be in a measure dependent upon 
the food, as might reasonably be expected, Carnivora giving milk 
possessing an acid reaction, and Herbivora an alkaline milk. Al- 
though apparently homogeneous, it may be separated into cream 
(which consists of oil globules, formed by thin envelopes of casein 
(curd), enclosing the fats of butter), curd, or casein, albumen, milk- 
sugar, and mineral matters, consisting chiefly of phosphate of lime and 
magnesia, as bone, earth, and salts of potassium and sodium, with 
some oxide of iron. 
Cream — varies in composition, according to the circumstances 
under which it is produced. Four different samples analysed in my 
laboratory yielded the following results :— 
I. 10 Il. IV. 
Water. . 74°46 64-80 56°50 61°67 
Butter (pure Tatty mutters) : 18°18 25°40 31°57 33°43 
*Casein .« , 2°69 ; Noe 2°62 
Milsusar oe tek aos | JT | 84H] T.56 
Mineral “natters (ash) pepo Oe 0 59 2°19 3°49 0°72 
: 100° 00 100-00 100-00 100°00 
* Containing nitrogen . 43 3g. O06 So. G9 “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 
10194 at 62° Fahr. The specific gravity of two other samples of 
