22 INTRODUCTION. 



Bodies formed in this way are called sulpho-com- 

 pounds, or, as they all possess the character of acids, 

 sulpho-acids. 



Frequently, however, the action of concentrated sul- 

 phuric acid consists in the elimination of the elements 

 of water from organic compounds, the latter being 

 completely destroyed (carbonized), or converted into 

 others containing less hydrogen and oxygen ; for ex- 

 ample: 



C 2 H 5 .OH = C 2 H 4 + H 2 0. 



Alcohol. Ethylene. 



When ammonia acts upon organic compounds, espe- 

 cially those which contain chlorine, bromine, or iodine, 

 bodies containing nitrogen are formed as a rule, the 

 halogens being eliminated and replaced by the group 

 ; for example : 

 C 2 H 3 C10 J 



Chloracetic acid. Arnidoacetic acid. 



The new compounds which result in this way are 

 called amides. They are also formed by the action of 

 hydrogen in statu nascendi (from tin and hydrochloric 

 acid), or of sulphuretted hydrogen upon nitro-com- 

 pounds, the group NO 2 contained in the latter being 

 transformed into NH 2 ; for example: 



6H = C 6 H 5 .mP -f 2H 2 0. 



Nitrobenzol. Anilin. 



The elementary composition of organic bodies can 

 be determined with the greatest exactitude. The ana- 

 lysis of the ordinary ones consists in the oxidation of 

 the carbon to carbonic acid, and of the hydrogen to 

 water, and the calculation, from the quantity of these 

 products of combustion, of the quantity of carbon and 

 hydrogen in the compound. Nitrogen is separated as 

 nitrogen and measured, or it is transformed into am- 

 monia. Oxygen is calculated indirectly by loss. 



The most common method of estimating carbon and 

 hydrogen consists in submitting an accurately w r eighed 

 quantity of the substance to be analyzed, with a large 



