150 Oil for dalicate Machinery. 
PRESERVING OBJECTS OF NATURAL HISTORY. 
M. Drapier, Professor of Chemistry and Natural History,and one 
of the Editors of the Annales Generales des Sciences Physiques,’”” 
has substituted with success, in lieu of the poisonous matters 
employed in preserving objects of natural history, a soap com- 
posed of potash and fish oil. He dissolves one part of caustic 
potash in water, and adds to the solution one part of fish oil: he 
rubs the mixture till it acquires a pretty firm consistence. When 
it is completely dry, he reduces it to powder with a rasp. One 
part of this powder is employed in forming a soft paste or liquid 
soap, by means of an equal quantity of a solution of camphor in 
musked alcohol. This liquid soap is well rubbed upon the skin 
of the bird, previously cleared of its fat, and the other part of the 
soap and powder is plentifully scattered hetween the feathers. 
Thus prepared, the bird is placed in a moist situation, in order 
that the particles of soap may soften and attach themselves per- 
fectly to the feathers, the down, and the skin. It afterwards is 
put in adry place. By this means it completely resists the at- 
tacks of larve, and has neither the danger nor the inconvenience 
of arsenical preparations, which, as is well known, stain and 
spoil the extremities of the feathers and down. 
TO PREPARE OIL PROPER TO BE APPLIED TO WATCH-WORK 
AND OTHER DELICATE MACHINERY. 
The oil best adapted for diminishing friction in delicate ma- 
chinery should be free from all acid and mucilage, and be capa- 
ble of enduring intense cold without freezing. The oil, in one 
word, should be pure ea/in free from even a trace of slearin. 
It is by no means difficult to extract the ealin from any of the 
fine oils and even from fats, by following M. Chevreul’s process, 
which consists in treating the oil in a matrass, with seven or 
eight times its weight of alcohol nearly boiling, decanting the 
liquid and suffering it to cool. ‘The stearin separates in the 
form of a crystalline precipitate. The alcoholic solution is then 
to be evaporated to one-fifth of its volume, and the ealin will be 
obtained ; which should be colourless and tasteless, almost free 
from smell, without action on mfusion of litmus, having the con- 
sistence of white olive oil, and not easily congealable. 
VACCINATION. 
Dr. Thompson, of Edinburgh, has started a new theory of vac- 
cination, viz. that it is not a certain preventive of small-pox, but 
that it is a better preservative than the small-pox itself. The 
Doctor is of opinion, that what is denominated chicken-pox is a 
true variolous disease, modified by previous small-pox or cow- 
pox, and that the chicken-pox is the mildest after vaccination . 
has been undergone, 
