Or - CORROSION. 377 
cefs, we have difcovered, that we may change the men- 
ftruum, without injuring the preparation at all, and em- 
ploy aqua fortis, or the nitrous acid in place of the fu- 
ming fpirit of falt; and that aqua fortis is even a more 
perfe& menftrum, than the {pirit of falt, in as much as 
the colour of the injection is thereby lefs changed, and 
the {mall veffels better preferved. Befides the difference 
of expence is confiderable, as the fpirit of falt is worth 
eighteen livres a pint, whilft the aqua fortis cofts at moft 
but two livres, and the effect is the fame for quantity. I 
have alfo employed the fpirit of nitre for the fame pur- 
pofe, with great fuccefs*.” 
In refpect to the fourth Principle, namely, the Addre/s of 
the Operator, and wherein it con/ifts. 
He ought to guard againft cutting away or removing 
the cellular and other furrounding parts, before he has 
made the injection. In fat, thefe give firmnefs to the 
veffels, and prevent their ftretching unnaturally, or affum- 
ing forms contrary to nature, from the impulfe of the in- 
jection when drove into them by the hand of the anato- 
mift. Thefe fubftances enable them to refift the too great 
extenfion and yielding to the force applied. 
The injecting pipes ought to be proportioned to the fize 
of the veflels through which the injection is to be made. 
It is proper to foak thofe parts in warm water, which 
we are about to inject, for a fhorter or longer {pace of time, 
as well to wafh them clean, as to carry off the blood and 
other fluids, and the better to difpofe thofe parts to receive 
the injeGtion, with which they are to be filled. 
The 
* Monf. Morgan, Docteur en medicine de Ia faculté d’Edinbourg, en a donné une defcrip- 
tion exacte a |’ Academie royale de la chirurgie, et c’eft de Ini que je tiens l’art de préparer ces 
parties; mais depuis aprés y avoir beaucoup travaillé, mon neveu et moi, et y avoir eu beau- 
coup de fuccés, nous avons decouvert qu’on pouvoit changer le menftrue, fans préjudicier 
en rien a Ja preparation, et employer, au lieu de fel fumant, l’eau forte, qui eft méme un 
menttrue plus parfait, que Pefprit de fel, puifque la couleur de Vinjection eft moins changée, 
et que les petits vaiffeaux font mieux conférvés. D/ailleursla difference eft encor bien grande 
pour la dépenfe, puifque l’efprit de fel vaut 18 liv la pinte, au lieu que l'eau forte ne coite 
tout au plus que 2 liv, et que la quantité eft la méme pour effet. J'ai employé aufli avec 
beaucoup de fuccés l’efprit de nitre. Anthropotomie, pag. $3. 84. 
