By CORROSION. 375 
the parts injeted in water, for the fake of wathing off the 
men{truum that we have made ufe of for performing the 
neceflary corrofion. 
Thefe injections are well fuited to make corroded pre- 
parations of the vifcera, as of the heart, lungs, liver and 
kidneys. Yet I doubt not but perfons of ingenuity, who 
fhall be at the pains to render themfelves converfant in 
the art of injeGion, by giving attention to every circum- 
fiance, will acquire further {kill and may find other fub- 
ftances, equally fit for injetion without being fo liable to 
become brittle, which thofe compofitions I have given 
above are, in fome degree, even when made with the ut- 
moft care and exacinefs. ; 
To know whether any fubftance of which a perfon wifh- 
es to make a trial for injection, will with{tand the action 
of the menftruum he means to employ, it is fufficient to 
put a piece of the compofition to be ufed as an injection 
into a {mall quantity of the menftruum, and let it remain 
in it for a week or fortnight; by that means he can judge 
of its goodnefs, before he is at the trouble of making, or of 
{poiling an injeCtion, as the cafe may happen. 
Of the CoLouRs. 
The colours we commonly ufe to diftinguith the differ- 
ent orders of veffels are, 1{t. Vermilion for colouring the 
injection for thearteries. 2d. Blue verditure, or what iscall- 
ed Pruffian blue, for the injection to be thrown into the 
veins. 3d. For colouring the injections to be thrown into the 
ureters and pelvis of the kidneys, and the tracheal veflels 
of the lungs, what are called in Englifh king’s yellow 
and flake white are moftly ufed. A variety of other co- 
lours may be employed, but thefe are the principal and 
the beft. 
We fhould obferve to melt the wax thoroughly over a 
flow fire, and the colouring powders fhould be added by 
degrees, ftirring them well in at the fame time, before the 
Bbb 2 other 
