450 
CAUSTICS. 
both these precipitates is accelerated by rubbing the surface 
of the tube with a glass rod. 
The precipitate formed by chromate of potash gets imme- 
diately a dark purple colour, if moistened by concentrated 
sulphuric acid. All the other precipitates get the same 
colour if they are dissolved in a small quantity of strong 
sulphuric acid, and the solution brought into contact with a 
fragment of a crystal of chromate of potash or ferridcyanide 
of potassium. 
ON CAUSTICS. 
M. E. Ferrand, in a paper addressed to the Societe des 
Sciences Medicales et Naturelles of Brussels, gives the follow- 
ing 
List of the principal Caustics : 
Ammoniacal 
Antimoniacal 
Silver 
Arsenic 
Gold 
Calci-potassic (of Vienna, 
Chloro-bromic 
Chromic 
Cupreous 
Mercurial 
Acid Mercurial 
Nitric 
Potassic 
Filhos) Stannic 
Sulphuric 
Zincic 
After which he proceeds to group or classify and comment 
on them thus : 
Alkaline Caustics . — Ammoniacal , Antimoniacal , and 
Calci-potassic . 
In general, caustic alkalies occupy the first rank with 
respect to the homogeniety of the result, the second place 
with regard to the extent of the action produced, and the 
last with respect to consistence. 
They have a dissolving action on the elements of the 
blood ; they attack the skin powerfully, and this property is 
characteristic; indeed, they are used in many cases, and 
their application at first becomes necessary, when we intend 
immediately to use a metallic caustic, as these last do not 
break the skin. 
With Muscles . — A soft, not very distinct, eschar, 3 milli- 
metres in thickness. 
Dried as far as possible in the air, the cauterized portion 
weighed two, when the product of an analogous cauterization 
weighed four with acid, and one with metallic caustics. 
