124 FINE CHEMICALS AND PHARMACEUTICS. [IV. 



cohol in chloroform by adding one or two crystals of cliromic 

 acid to 2 drachms of the suspected mixture. If it contains 

 alcohol, the acid is soon reduced to green oxide. (Journ. de 

 Chim. Med. iv. 257.) 



On the tests and purification of chloroform, by Dr. Grego- 

 ry, see Chem. Gaz. viii. 189. The method was afterwards 

 shown to be defective, rendering the chloroform liable to 

 decomposition. 



Collodion. — Maynard (Silliman's Journ.) was the first to 

 propose an ethereal solution of gun-cotton as a substitute for 

 adhesive plaster. The ordinary gun-cotton is, however, some- 

 what insoluble in ether. It must therefore be prepared by a 

 special method, known as Malgaigne's (Lond. Med. Gaz. 1848), 

 which gives a perfectly soluble product. 



Mix together, in a stone pan, 40 oz. purified nitre in powder, 

 with 60 oz. of sulphuric acid of 66°, and stir in 2 oz. of 

 finely-carded cotton. After 3 minutes, remove the cotton 

 with a glass rod and plunge it into a large volume of water, 

 and renew the washing with fresh water until the removal of 

 all acidity. Press, dry in a warm room, and pull out the 

 wool. 8 oz. of this cotton form, with 125 pts. of rectified 

 ether, a ready solution, which must be diluted with 8 pts. of 

 rectified alcohol and strained through a linen cloth. 



The liquid is the collodion of the shops, now much used for 

 surgical purposes. It is applied either alone with a brush, or 

 upon a linen cloth. Its adhesiveness is said to be increased 

 by the addition of Venice turpentine. The parts to which it 

 is to be applied must be free from all dampness, as water de- 

 composes the collodion. 



When containing one grain of morphin to the ounce, it is 

 also a very efficient remedy for the toothache. 



As the solvent of ethereal extract of cantharides, it is an 

 admirable blistering-plaster. It may be spread on with a 

 camel's hair pencil. The evaporation of the ether leaves a 

 dry coating in a few seconds ; and as soon as the principle 

 of the cantharides begins to act upon the epidermis, the coat- 

 ing rises and forms a blister. If opened at the side, the film 



