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*Ie foap which it m-lght retain. When thus wafiied it 
was dried, then treated thrice -fucceffively with two litres 
of boiling alcohol cf the gravity of o‘820 divided into 
three equal portions; the firft congealed almoft wholly 
upon cooling, the fecond was fiightly difturbed, and the 
third fcarcely at all. The rtfidue, infoluble in alcohol, 
weighed rather more than two grammes (about 38! grains) ; 
it refembled the mother-of-pearl Jubilance ; it was different, 
however,, from the part which was diffolved. The expe¬ 
riment taught me that the mother-of-pearl fubftance was 
formed of a fatty fubftance, abfolutely new, combined 
with potafh, lime, and oxyd of iron ; and that, when we 
treated it with boiling alcohol, we diffolved the combina¬ 
tion of potafh, and a little of thofe of lime and oxyd of 
iron, while the latter, infoluble or much let's foluble than 
the former, formed the refidue. I convinced myfelf of 
thefe fafts by treating in the following way the depcfi- 
tions which were Separated from the alcoholic wafhings 
by cooling and concentration comparatively with the re¬ 
fidue. I put fome very dilute muriatic acid into two por¬ 
celain capfules; to the one I added fome mother-of-pearl 
fubltance which was Soluble in alcohol, and to the other 
the reSdue. On heating them, the acid was combined 
with the falifiable bafes, and the melted fatty fubltance 
was feparated from the liquid. After keeping this fub¬ 
ltance in fufion in diftilled water, and leaving it to be¬ 
come Solid by cooling, I added the walkings to the acid 
liquids, and evaporated to drynefs. I found that 100 parts 
of Soluble matter had given to the muriatic acid 0-06 
of lime and oxyd of iron, and 8‘o7 of potalli ; while the 
refidue had given to this acid lime, oxyd of iron, and a 
mere atom of potalli. The fatty fubftance, feparated from 
the falifiable bafes, was diffolved in boiling alcohol; on 
cooling, it was obtained cryltallized and very pure, and 
in this date it was examined. As it lias not been hitherto 
<iefcribed, it ought to be diftinguiflied from other fub- 
Itances by a peculiar name ; consequently I purpofe to 
call it margarine, from the Greek word fignifying pearl, 
becaufe one of its characters is to have the appearance of 
mother-of pearl, which it communicates to Several of the 
combinations which it forms with the falifiable bafes. It 
is of a pearly white, and taftelefs. Its fmell is feeble, and 
a little Similar to that of white wax. It is lighter than 
water. At ^S' Z ’S Reaumur it melts into a very limpid 
colouriefs liquid, which cryftallizes upon cooling into 
brilliant needles of the finelt white. When we diftilled 
it, it melted, and exhaled a white vapour which was de- 
yofited in a farinaceous-like matter in the neck of the 
retort. It boiled, and foon afterwards emitted an invifi- 
ble vapour, which was condenfed into a liquid, and then 
into a white concrete mafs. At the fame time there was 
produced a little acid water, which was indebted for this 
property to vinegar, and perhaps fome febacic acid, and a 
itrong fmell, which I am inclined to attribute to a com¬ 
bination of volatile empyreumatic oil and acetic acid; 
When the matter contained in the retort began to turn 
black, and the product extricated from it was coloured 
yellow, I changed the recipient, and continued the fire 
until there was no longer any thing volatilized ; very little 
gas or liquid w as formed, and almolt the whole of the pro- 
duft.was folid. Four grammes (6if grains) of margarine 
yielded o‘oq-5 gramme (about "343a grain) of charcoal, con¬ 
taining an atom of lime, iron and potafh, a firft product, 
which was very white, weighing 2 - i9grammes (33 grains), 
a fecond producl, coloured yellow, weighing 1-45 gramme, 
(22 grains.) 
Margarine is infoluble in water. It is extremely folu- 
ble in alcohol ; for 100 parts of the latter, of the gravity 
of 0 816, diffolved, at 75 0 , iSo^ parts. Upon cooling, it 
congealed into a folid mafs : this mafs had a greenifh fhade, 
which became particularly evident in thole parts of the 
centre where a hole was made with a glafs fpatula. This 
phenomenon feemed to be owing to the.alcohol; for the 
oqtour difappeared on the evaporation of this liquid. 
When the margarine is depofited by. a gradual cooling, 
from a folution which is not fatursted with it, it crylta- 
lizes in frnall needles which unite in liars. The mother- 
of-pearl fubftance is lefs foluble in alcohol than margarine, 
too grammes of this liquid of a gravity of ©'834 only dif- 
folvetl 31-37 at a temperature of 67° centigrade. This 
folution becomes turbid upon cooling ; and this ought to 
be the cafe, fince one part of mother-of-pearl matter re¬ 
quires 318 of alcohol to be diffolved at the temperature of 
20° centigrade ; it does not change the colour of hematinei; 
which proves that the potafh is more ftrongly attracted by 
the margarine than by the colouring principle. The mat¬ 
ter which was precipitated from the alcohol, hy water, 
re-diffolved twice in the alcohol, was depofited upon cool¬ 
ing in the ftate of true mother-of-pearl matter, which con¬ 
tains 100 of margarine and 8’88 of potafh. 
The combination of margarine faturated with potafh 
prefects the following properties: It is white, and not fo 
j'oft to the touch as the pearly matter. It has a very 
flight alkaline tafte. When we put it into pure water, it 
is decompofed into a pearly matter, and into potafh. 
We may be convinced of this by putting it into abun¬ 
dance of cold water, and fhaking the mixture from time 
to time. The matter thrown upon a filter, and wafhed, 
yielded margarine xoo, and potafh 8‘55. The wafhings, 
when filtered and evaporated, contained potafh and a trace 
of margarine. If, inllead of putting the combination of 
margarine faturated with alkali in plenty of water, we put 
it in a fmall quantity of this liquid, it fw.ells, becomes l'emi- 
tranfparent by abforbing it, and forms a thick mucilage, 
which exhibits pearly matter when it is fbaken. In this 
cafe, the mafs of water not being fufficient to overcome 
the whole of the affinity of the pearly matter for an ex- 
cefs of potafh, it happens, that the decompofition of the 
faturated combination is only partial ; and it is the part 
which is not altered which abforbs the water, and forms 
with it a mucilaginous liquid, by retaining it among its 
molecules. If we throw the whole upon a filter, after 
having mixed enough of water with it to facilitate the 
filtration, analyfis demonftrates lefs potafh than in the fa- 
turated combination, and more than in the pearly matter-; 
which proves that the decompofition has been but partial. 
When we put three grammes of faturated combination in 
100 grammes of boiling water, we obtain a folution which 
is perfectly limpid while the liquor is warm, and which 
even may be filtered. This folution upon cooling depo- 
fits abundance of mother-of-pearl matter, and afterwards 
becomes thick. When it is completely cooled, it is pr%. 
cifely like cold water in which we have put a great quan¬ 
tity of pearly combination ; only the mucilage is much 
more homogeneous. The filtered liquor contains potafh 
and fome atoms of margarine; for it is not rendered tun. 
bid by the acids, except when it has been concentrated. 
It follows from what has been faid ; 1. That the fatu¬ 
rated combination of margarine is decompofed into mo¬ 
ther-of-pearl fubltance, and into potafh, by a great mafs 
of cold water. 2. That a little of this liquid only de- 
compofes a part of it; that what is not decompofed ab¬ 
forbs water, and forms a thick femi-tranfparent mucilage. 
3. That, when the aftion of the water is affifted by that 
of caloric, the faturated combination may be completely 
diffolved ; and that by cooling there is formed pearly mat¬ 
ter, and a thick mucilage of faturated combination, if the 
water be not always in excels. 
Margarine decompofes the fhbcarbonate of potafh. We 
may render the decompofition evident, by paffing into a 
tube full of mercury a mixture of eight parts of water, 
one of margarine, and half a part of fubcarbonate* and b'y 
heating it afterwards with a red-hot iron to ebullition. 
After cooling, we find a gafeous refidue, which is pure 
carbonic acid. By repeating the experiment in a fmall 
phial furnifhed with a curved tube, I obferved that the 
margarine was diffolved before there was any extrication 
of carbonic gas, and that this extrication only took place 
when 
