IDO 
il, as nitric acid. By means of this last acid, 
as Berthollet discovered, a quantity of azotic 
gas may be obtained from curd. 
Curd, as is well known, is used in making 
cheese; and the cheese is the better tin; more 
it contains of cream, or of that oily matter 
v. lie h constitutes cream. It is well known 
to cheesemakers. that the goodness of it de- 
pends in a great measure on the manner of 
separating the whey from the curd. If the 
milk is much heated, the coagulum broken 
in pieces, and the whey forcibly separated, 
as is the practice in many parts of Scotland, 
the cheese is scarcely good for any thing ; 
but the whey is delicious, especially the 
whey last squeezed out, and butter may be 
obtained from it in considerable quantity, 
i his is a full proof that nearly the whole creamy 
part of the milk has been separated with the 
whey. Whereas if the milk is not too much 
heated (about 100 degrees is sufficient), if 
the coagulum is allowed to remain unbroken, 
and the whey separated by very slow and 
gentle pressure, the cheese is excellent ; but 
the whey is - almost transparent, and nearly 
colourless. 
Good cheese melts at a moderate heat ; 
but bad cheese, when heated, dries, curls, 
and exhibits all the phenomena of burning 
horn. Hence it is evident, that good cheese 
contains a quantity of the peculiar oil which 
Constitutes the distinguishing characteristic of 
cream ; whence its flavour and smell. 
1 his resemblance of curd and albumen 
makes it probable that the coagulation of 
milk and albumen depends upon the same 
cause. Heat, indeed, does not coagulate 
milk, because the curd in it is diluted with 
too large a quantity of water ; but if milk is 
boiled in contact with air, a peliicle soon forms 
on its surface, which has the properties of curd. 
If this pellicle is removed, another’ succeeds ; 
and bv continuing the boiling, the whole 
of the curdy matter may be separated from 
milk. When this pellicle is allowed to re- 
main, it falls. at last to the bottom of the ves- 
sel ; where, being exposed to a greater heat, 
it becomes brown, and communicates to milk 
that disagreeable taste which, in this country, 
is called a singed taste. It happens more rea- 
dily when milk is boiled along with rice, 
flour, &c. 
If to boiling milk there is added as much 
of any neutral sale as it is capable of dissolv- 
ing, or of sugar, or of gum arabic, the milk 
coagulates and the curd separates. Alcohol 
also coagulates milk; as do all acids, ren- 
net, and the infusion of the Powers of arti- 
choke and of the thistle. If milk is diluted 
with ten times its weight of water, it cannot 
be made to coagulate at all. 
3. U hey, after being filtred to separate a 
quantity oi curd which still continues to float 
through it, is a thin pellucid fluid, of a yel- 
lowish-green colour and pleasant sweetish 
taste, la which the flavour of milk may be dis- 
tinguished. It always contains Some curd: 
nearly the whole may be separated by keep- 
ing the whey for some time boiling ; *a thick 
white scum gathers ou the surface, which is 
known by the name of skim-curd. When 
this scum, which consists of the curdy part, 
is carefully separated, the whey, after being 
allowed to remain at rest for some hours' to 
give the remainder of the curd time to preci- 
pitate, is decanted off almost as colourless us 
MILK. 
water, and scarcely any of the peculiar taste 
of milk can be distinguished in it. If it is 
now slowly evaporated, it deposits at last a 
number of white-coloured crystals, which are 
sugar of milk. Towards the end of the eva- 
poration, some crystals of muriat of potass 
and of muriat of soda make their appearance. 
According to Scheele, it contains also a little 
phosphat of lime, which indeed may be pre- 
cipitated by ammonia. 
After the salts have been obtained from 
whey, what remains concretes into a jelly on 
cooling. Hence it follows that whey also 
contains gelatine. Whey, then, is composed 
of water, sugar of milk, gelatine, muriat of 
potass, and phosphat of lime. The other 
salts which are sometimes found in it, are 
only' accidentally present. 
If whey is allowed to remain for some time, 
it becomes sour, owing to the formation of a 
peculiar acid known by the name of lactic acid. 
It is to this property of whey that we are to 
ascribe the acidity which milk contracts; for 
neither curd nor cream, perfectly freed from 
serum, seems susceptibleof acquiring" acid pro- 
perties. Hence the reason also that milk, af- 
ter it becomes sour, always coagulates. Boil- 
ed milk has the property’ of continuing longer 
sweet, but it is singular enough that it runs 
sooner to putrefaction, than ordinary milk. 
The acid of milk differs considerably from 
the acetic : yet vinegar may be obtained 
from milk by' a very simple process. If to 
somewhat more than 8 lbs. troy of milk six- 
spoonfuls of alcohol are added, and the mix- 
ture well corked is exposed to a heat sufficient 
to support fermentation, provided attention 
is paid to allow the carbonic acid gas to escape 
from time to time, the whey-, in about 
a month, will be found converted into vine- 
gar. 
Milk is almost the only animal substance 
which may be made to undergo the vinous 
fermentation, and to afford a liquor resem- 
bling wine or beer, from which alcohol may 
be separated by distillation. This singular 
fact seems to have been first discovered by 
the Tartars; they obtain all their spirituous 
liquors from mare’s milk. It has been ascer- 
tained, that milk is incapable of being con- 
verted into wine till it has become sour; af- 
ter this nothing is necessary but to place it in 
the proper temperature; the fermentation 
begins of its own accord, and continues 
till the formation of wine is completed. 
Scheele had shewed that milk was capable 
of fermenting, and that a great quantity of 
carbonic acid gas was extricated from 
it during this fermentation ; but he did 
not suspect that the result of this fermenta- 
tion was the formation of an intoxicating 
liquor similar to wine. The Tartars call 
the vinous liquid which they prepare koumiss. 
A very exact account of its preparation anti 
medical uses lias been published by Ur. Guth- 
rie. 
When milk is distilled by the heat of a 
water-ba ll, there comes over water having 
the peculiar odour of milk: which putrefies ; 
and consequently contains, besides mere wa- 
ter, some of the other constituent parts of 
milk. After some time the milk coagulates, 
as always happens when hot albumen ac- 
quires a certain degree of concentration. 
There remains behind a thick unctuous yel- 
lowish-white substance, to which Hoffman 
gave tke name offranchippan. This sub- 
stance, when the lire is increased, yields at 
first a transparent liquid, which becomes gra- 
dually more coloured ; some very fluid oil 
comes over, then ammonia, an acid, and at 
last a very thick black ofl. j owards the end 
of the process carbureted hydrogen gas is dis- 
engaged. There remains in the retort a 
coal which contains carbonat of potass, muriat 
of potass, and phosphat of lime ; and some- 
times magnesia, iron, and muriat of soda. 
J hits we see that cow’s milk is composed 
of the following ingredients: 
1. Water, 6. Muriat of soda, 4 
2. Oil, 7. Muriat of potass, 
3. Curd, 8. Sulphur, 
4. Gelatine, 9. Phosphat offline. 
5. Sugar of milk. 
-The milk of all other animals, as far as it 
has hitherto been examined, consists nearly of 
the same ingredients: but there is a very 
great difference in their proportion. 
W oman’s milk has a much sweeter taste 
than cow’s milk. W hen allowed to remain 
at rest for a sufficient time, a cream gathers 
on its sui face. T his cream is more abundant 
than in cow s milk, and its colour is usually 
much whiter. After it is separated, the milk 
is exceedingly thin ; and hasThe appearance 
rather of whey with a blueish-white colour, 
than of cream-milk. 
None of the methods by which cow’s milk 
is coagulated succeed in producing- the coa- 
gulation of woman’s milk. It is certain, 
however, that it eontainscurd ; for if it is boiled* 
pellicles form on its surface, which have all 
the properties of curd. Its not coagulating, 
thuefore, must be attributed to the great 
quantity of water with which the curd ?s di- 
luted. 
Though the cream is churned evei;«*o long, 
no butter can be obtained from it ; but if* 
after being agitated for some hours, it is al- 
lowed to remain at rest for a day or two, it 
separates into two parts: a fluid which occu- 
pies the inferior part of the vessel, pellucid 
and colourless like water; and a thick white 
unctuous fluid which swims on the surface. 
! in lowei most fluid contains sugar of milk 
and some curd; the uppermost does not dif- 
fer from cream except in consistence. The 
oily part of the cream, then, cannot be sepa- 
rated by agitation from the curd. ’Phis cream 
contains a greater portion of curd than the 
cream of cow’s milk. 
When this milk, after the curd is separated 
from it, is slowly evaporated, it yields crys- 
tals of sugar of -milk and of muriat of soda. 
The quantity of sugar is rather greater than 
in cow’s milk. According to Haller, the sugar 
obtained from cow’s milk is to that obtained 
from an equal quantity of woman’s milk as 33 
to 58, and sometimes as 37 to 67, and in all 
the intermediate ratios. 
Thus it appears that woman’s milk dif- 
fers from that of cow’s in three particulars : 
It contains a much smaller quantity of curd. 
Its oil is so intimately combined with its curd 
that it does not yield’ butter. It contains ra- 
ther more sugar of milk. 
Parmentier and Deyeux. ascertained, that 
the quantity of curd in woman’s milk increases 
m proportion to the time after delivery. 
Ncai iy ihe same thing lias been observed 
with respect to cow’s milk, 
