CHEMISTRY. 
360 
and a fat fubftance. Bat Morveau, after examining the 
experiments of this chemift: with his ufual accuracy, and 
comparing them with thofe of Scheele, has fliown in the 
new DiSlionnaire Encyclopedique, that Hermftadt has not 
accpmplifned his undertaking, and that, even from his 
own refults, the difcovery of Scheele is rather confirmed 
than deftroyed. Morveau has likewife made feveral in¬ 
genious experiments which confirm this affertion. To 
thele accounts we may add, that the oxalic and faccho- 
la-6lic acids do not exift ready formed in fugar of milk, 
and that this fait contains only the bafes, which take the 
oxygen or acidifying principle from the nitric acid. We 
may likewife obferve, that fubfequent experiments will 
probably (how, that the faccholadticacid is nothing more 
than a modification of fome other vegetable acid ; for 
every circumftance tends to prove, that the principles of 
whey are derived from the vegetables on which the ani¬ 
mals fubfift. 
The following appears to be the molt convenient pro- 
cefs for obtaining faccholaftic acid. It is given by Boyl- 
fon, Mem. Soc. Med. 1787-8. 619. One ounce of fugar 
of milk was dilfolved in water, and the folution evapo¬ 
rated to two ounces, which were digefted for feveral days 
in a gentle heat, with nine drachms of nitric acid. When 
evaporated to the confidence of honey, the mixture was 
diluted and filtered, the lacchola£Iic acid, which had 
been formed, remaining in a white powder on the filter¬ 
ing paper. A frefh quantity of nitric acid was added to 
the filtered liquor, and the former procefs repeated, till 
■the whole of the fugar of milk was converted into fac- 
.choladtic and oxalic acids. By this method, one ounce 
of faccholaftic acid, and nine drachms forty-eight grains 
of oxalic acid, were procured from four ounces of fugar 
of milk and feventeen ounces of nitric acid. 
Whey, when prepared with new milk, contains a fac- 
charine elfential fait, but it loon acquires an acid tafte, 
hy the eftabliihment of the fermentation. This change 
is produced by the alterationof a mucilaginous principle, 
^contained in themilk; and it is the developement of this 
acid which occafions the fpontaneous feparation of the 
whey from.the other fubftances contained in milk. It is 
■therefore necelfary to examine the acid, which is formed 
in milk, and conftitutes fermented whey. It is a well- 
known fa6t, that milk left expofed in a temperature of 
feventy or eighty degrees, experiences, in a few days, a 
•fermentation which developes an acid, and feparates the 
butter and cheefe. The acid, formed by this fermenta¬ 
tion, and which is as ftrong as it will be at the end of 
twelve or fifteen days, has been examined by Scheele, 
and is called the lattic acid. The following is the procefs 
ufed by Scheele, to obtain it in a Hate of purity. After 
having attempted, in vain, to feparate the acid by dif- 
.tillation from four whey, by which he obtained only a 
frnall quantity of vinegar, he evaporated the whey to 
one-eighth, after having filtrated it, to feparate all the 
cafeous matter. From this he precipitated the animal 
earth, by lime water. He then diluted the fluid with 
-three times its weight of water, and feparated the lime 
by the oxalic acid ; at the fame time taking care that this 
laft acid Ihould not remain difengaged in the folution, 
which was ealily afcertained and prevented, by the addi¬ 
tion of fucceflive fmall portions of lime-water. After 
evaporating the liquor to the confidence of honey, the 
fugar of milk, and feveral other foreign fubltances, were 
then feparated, by the addition of alcohol, which ealily 
diflolves the laftic acid. Laftly, The decanted folution 
being diltilled, the alcohol palled over, and the pure 
laftic acid remained in the retort. Scheele has oblerved 
following properties in this acid. 
When ftroiigly evaporated, it did not afford cryftals, 
but attrabfcd the humidity of the air: by diftillation, it 
afforded an empyreumatic acid, refembling pyrotararous 
.acid ; a fmall quantity of oil, and a mixture of carbonic 
acid gas, and of carbonated hydrogen gas. With the 
three alkalis, and alio with barytes and lime, it forms de- 
liquefcent faits. Its combination with magnefia cryftal- 
lizes, blit likewife attracts the moilture of the air. The 
greater part of thefe lalts, or alkaline and earthy lattats, 
are foluble in alcohol. It does not at all attack cobalt, 
bifmuth, antimony, mercury, filver or gold, even by the 
heat of ebullition. It diflolves zink and iron, producing 
hydrogen gas ; the firft of thefe faits, called the ladhit of 
zink, cryftallizes ; the fecond, or the lablat of iron, forms 
a brown deliquelcent mifs. The labtic acid oxydates, 
and diflolves copper and lead. The lattic folution of 
the latter metal depofits a fmall quantity of fulphat of 
lead, which indicates the prefence of a fmall quantity of 
fulphuric acid in this animal acid. Laftly, It decompofes 
the acetit of potafli; a property, which, together with 
moft of thofe here mentioned, denotes that the laddie acid 
differs from vinegar. Scheele adds, likewife, that a true 
vinegar may be obtained from milk, by mixing fix fpoon- 
fuls of alcohol with three pints of milk, and fuffering the 
mixture to ferment in a well-clofed veffel. The gas, which 
is difengaged during the fermentation, muff: be fuffered 
to efcape from time to time ; and at the end of a month 
the milk is changed into good vinegar, which may be" 
ftrained through a cloth, and preferved in bottles. This 
celebrated German chemift likewile adds, that milk, in 
a bottle whole neck is plunged in a veffel fided "with the 
fiime liquor, and expofed to a heat fomewhat ltronger than 
that of fummer, undergoes a fermentation which affords 
a large quantity of elaltic fluid. This laft fluid difplaces 
the milk, and almoft entirely empties the bottle, at the 
end of two days. The acid produced in this fermenta¬ 
tion, which takes place without the contabf of air, ap¬ 
pears to receive its oxygen, or acidifying bafe of the air, 
from the decompofition of the water. 
Earths and alkalis have a fenfible aftion on whey. 
Lime and barytes afford a plentiful precipitate, which is 
phofphat of lime; with potafh there is alfo phofphat of 
lime, whence it might be fuppofed to be contained in it. 
With acids, the whey thickens, but heat is requifite ; 
fulphats or other faits are produced according to the acid 
employed, but neither muriats nor pholphats. The ox¬ 
alic acid demonftrates the prefence of lime in whey ; phof- 
phats of lime and of foda are obtained. The metallic 
faits fliew that pholphorus is contained in whey. With 
nitrat of mercury, a precipitate is obtained compofed of 
the nitrat and phofphat of mercury. 
Of Cheese.— We have feen tiiat the folid mafs, or 
cream, which rifes to the furface of the milk, contains 
two other principles, cheefe and butter. When cheefe is 
prepared for the table, the butter is not feparated ; it is 
lweeter and more pleafant. Whether white and loft, or 
yellow and firm, cheefe is a mixture of feveral fubftances, 
which a chemift diltinguifhes from what is called merely 
the cafeous part. Clieeie dried, and put in a proper place 
to experience a beginning of putrid fermentation, ac¬ 
quires confidence, tafte, and colour. There are various 
lorts of cheefe. For making cream-cheefe, curdle the 
milk quickly with rennet, let all the whey be drained 
from it, then wall; it repeatedly in very pure water. The 
aftion of a gentle heat hardens it. Diftillation on a wa¬ 
ter-bath extrafts an infipid phlegm, which putrefies. 
Dried cheefe, diftilled in a retort, affords an ammonia- 
cal phlegm, a ponderous oil, and much ammoniacal car- 
bonat. Its coal is denle, very difficultly incinerated, and 
does not afford fixed alkali. When this coal is treated 
with nitric acid, it is found to contain lime, and the 
pholphoric acid. 
Cheefe putrefies in a hot temperature; it fwells, emits 
a naufeous lfnell, becomes imperfeftly fluid, and is co¬ 
vered with a feum, or froth, arifing from the dilengage- 
ment of a very ftrong-fimelling and mephitic gas, which 
efcapes with difficulty from this vifcid matter. Cheefe 
is inioluble in cold water ; hot water hardens it. Scheele 
has oblerved, that, when it has been precipitated by a fo¬ 
reign acid, boiling water diflolves a part. Treated with 
potalh, ammoniac is produced. Alkalis diflolve it in 
general. 
