112 TRANSACTIONS OF THE [MAR. 21, 



of estimating them, and, together with his pupils Will and Varren- 

 trapp, invented the methods of analysis which we practise to-day. 



lu 1832 Liebig and Wohler discovered the radical or parent sub- 

 stance of benzoic acid. They also noted that oil of bitter almonds 

 could be oxidized and gave benzoic acid. It followed, therefore, 

 that there must be some connection between benzoic acid and the 

 oil of bitter almonds. It had been previously ascertained that 

 benzoic acid could be obtained from aromatic gum benzoin. Then 

 Mitscherlich, another chemist, found that by heating benzoic acid 

 with lime he obtained benzol, a liquid hydrocarbon ; therefore there 

 must be some connection between this hydrocarbon and oil of bitter 

 almonds, for the oil gives benzoic acid and benzoic acid gives benzol. 

 Further, Mitscherlich converted benzol into benzoic acid again by 

 oxidation. It was ultimately ascertained that oil of bitter almonds 

 is an intermediate product between benzol and benzoic acid ; and 

 when Hoffmann discovered benzol in coal-tar in the year 1845 a 

 source for making it artificially was obtained. 



But to return to the vital-force theory. 



In 1835 or 1836, Berthelot, the Frenchman, succeeded in uniting 

 carbon and hydrogen and produced the hydrocarbon called acety- 

 lene, consisting of two atoms of carbon united to two atoms of 

 hydrogen. This was accomplished by using a powerful electric 

 battery, and allowing the sparks to pass between two carbon poles 

 in an atmosphere of hydrogen gas. Here w^as an actual union of 

 the very elements themselves to produce a compound characteristic 

 of organic substances, a hydrocarbon that up to that time had only 

 been obtained by decomposing organic compounds, such as car- 

 bonized tartar and water, wood-alcohol, and ether, by passing the 

 vapors through red-hot tubes. 



From this gas acetylene, the hydrocarbon ethene, or olefiant gas, 

 was made by acting on it with nascent hydrogen. By absorbing 

 olefiant gas in sulphuric acid a compound is formed which was 

 called sulphovinic acid, or ethyl acid sulphate. When this is boiled 

 with water we get ethyl hydroxide or alcohol and sulphuric acid. 

 From this series of steps it is evident that, starting from the ele- 

 ments themselves, we are able to build up compounds that are 

 entirely characteristic of organic substances, and this without the 

 intervention of any vital force. This sounds rather complicated, 

 but is only so in words. The process is simple. 



It was in the efforts to obtain knowledge of the active principles 

 of animal and vegetable substances used in medicines that many of 

 the greatest discoveries in organic chemistry were made. 



In 1803, Derosne, in Paris, discovered morphine and narcotine in 

 opium, and called the mixture a salt of opium. He also .knew it 

 was a base like ammonia. 



Sertiirner, a German apothecary, in 1806, discovered that mor- 

 phine existed in opium conil)ined with an acid, called meconic acid. 

 This discovery started the search for alkaloids in plants, as up to 



