CHEMISTRY. 523 



but Albert Niemauii, of Goslar, subsequently made a more thorough 

 study of the leaves and extracted the alkaloid, which he called cpcaine. 

 Niemann's process was as follows : 



The leaves were exhausted with alcohol (85 per cent.), to which was 

 added 2 per cent, of sulphuric acid, and to the resulting tincture milk 

 of lime in sufficient quantity. The mixture was filtered, the filtrate 

 neutralized with sulphuric acid, and the alcohol distilled off. The resin 

 was separated from the sirui^y residue by treating with water, and so- 

 dium carbonate then added. The deposited matter was then exhausted 

 by ether, and the ethereal solution, after most of the ether had been 

 distilled, was allowed to evaporate. The crystals were obtained mixed 

 with a dark-yellowish matter having a disagreeable odor from which, 

 however, they can be separated by washing with cold dilute alcohol. 



Purified by recrystallization, cocaine forms colorless transparent 

 prisms, inodorous, of a bitterish taste, soluble in 704 parts of cold water, 

 more soluble in alcohol, and freely so in ether. The solution has an 

 alkaline reaction and a bitterish taste, leaving a peculiar numbness on 

 the tongue, followed by a sensation of cold. The alkaloid melts at 

 1)7^.7 G. (208OF.), and on cooling congeals into a transparent mass, which 

 gradually becomes crystalline. Heated above this point it changes 

 color and is decomposed. It is inflammable, boiling with a bright flame 

 and leaving charcoal. With acids it forms crystallizable salts, which 

 are more bitter than the alkaloid itself. The comjiosition of this al- 

 kaloid, as determined by Losson, is C17H21NO4. 



Its combination with hydrochloric acid, commonly called the hydro- 

 chlorate, crystallizes in white, slender needles, easily soluble in water. 

 As stated in Watts' Dictionary of Chemistry, Vol. I, p. lOGO (1866), "it 

 has a bitter taste and produces on the tongue temporary insensibility." 

 This interesting observation, after eighteen years, has borne abundant 

 fruit. Br. Roller, of Vienna, again noticed its i)Ower of benumbing sen- 

 sation during the course of some experiments on lower animals ; a 5 per 

 cent, solution of the hydrochloride of cocaine dropped into the animal's 

 eye entirely deprived the eye of sensation. Roller at once proceeded to 

 exi)eriment on himself and in the hospital, with astonishing results. lie 

 communicated his discovery to the International Ophthalmological Con- 

 gress held at Heiddberg in September, and his results were speedily 

 confirmed by a host of experimenters. 



Its chief use is in connection with oi)erations on theoye. A few drops 

 of a 4 ])er cent, solution are introduced into the eye, and if necessary 

 i-ept'ated after a minute or two, until the organ loses entirely its sen- 

 sitiveness. The loss of sensation begins in three to five minutes and 

 continues from fifteen minutes to half an hour, the eflect being super- 

 ficial. The insensibility is not absolute. The i)afieut feels the opera- 

 tion as he would feel anything laid on his hand or arm, but the sense 

 of pain is almost wholly destroyed. Usually there is a slight feeling, 

 which is said by the patient to ;)e not worth mentioning. 



