GOSSYPIUM HERBACEUM 49 



(nom. vulg. Pernambuko, Tag.), and the G. arboreum, L. (Bulak 

 na bundok, Bulak net totoo, Tag.). 



Cotton is used extensively in bacteriological laboratories as a 

 filter of liquids and gases. This property possessed by cotton, 

 of retaining in its fibers the germs of the air was utilized by 

 the famous French surgeon Guerin in the treatment that bears 

 his name. The denuded surfaces exposed to infection by air- 

 borne bacteria are completely protected against them when, ac- 

 cording to the Guerin treatment, they are enveloped in large 

 masses of fresh, raw cotton, presumably free from microorgan- 

 isms. To avoid the possibility of infection by the cotton itself, 

 it is now the practice to sterilize it either by means of chemicals 

 such as carbolic acid, iodoform, etc., or by physical means such 

 as high temperatures. 



Raw cotton is used in compounding gun cotton or explosive 

 cotton, also named pyroxylin, and this is used to make collodion, 

 so extensively employed in medicine. 



Pyroxylin is made by treating cotton with equal parts of 

 nitric and sulphuric acids, then washing with water till the 

 latter ceases to give a precipitate with chloride of baryta ; then 

 dry in the air. 



Collodion is made by dissolving 5 grams of pyroxylin in the 

 following mixture : 



Sulphuric ether, rectified 75 grams. 



Alcohol at 95 20 " 



Filter. 



Elastic collodion : 



Canada Balsam 1.50 grams. 



Castor oil 50 



Collodion 30.00 



Mix. 



BOTANICAL DESCRIPTION. A plant 2-3 high, of herba- 

 ceous stem, branches sparsely covered with small, black points ; 



