56-(26) chemistry axd the question or ltfe. 



the old bonds of chemical attraction and establishing new 

 ones. Such products do not exist in the body analyzed, 

 but have their birth during the process which reveals 

 them. They are in no sense constituents ; they are simp- 

 ly products of chemical action during the analysis. When 

 for example alcohol vapor is passed through a red hot 

 tube several new substances issue, among which are (defi- 

 ant gas and benzine. Neither benzine nor olefiant gas 

 can be regarded as a constituent of alcohol. No chem- 

 ist has ever claimed them to be constituents of this sub- 

 stance. But it is known in regard to them that both are 

 compounds of hydrogen and carbon, that these elements 

 are contained in alcohol, and that the heat that destroys 

 the alcohol drives the atoms of these elements into new 

 combinations, which then, for the first, exist as .benzine 

 and oleliant gas. What then does analysis teach us 

 about the composition of alcohol ? Absolutely nothing 

 with certainty, beyond the names and the proportional 

 parts of the elements which it contains. Notwithstand- 

 ing the several compounds which alcohol yields by de- 

 composition, yet when asked for the exact catalogue of its 

 constituents, the analyst must conline his answer to the 

 elements carbon, hydrogen and oxygen. 



In mineral chemistry the cases are very rare in 

 which a compound can be with any certainty declared to 

 be a constituent of one more complex ; but in organic 

 chemistry such cases are not uncommon. 



I have referred to sugar and starch as familiar exam- 

 ples of compounds which are constituents of plants, and 

 have' said that we must so regard them because they are 

 not produced by the effort to extract them, but do, oil 

 the contrary, exist preformed in the plant from which 

 we get them. 



Many such proximate constituents of plants have a 

 definite chemical composition. We find for example 

 that starch is a single componnd. It is composed of car- 

 bon, hydrogen and oxygen, and contains these ele- 

 ments in the definite ratio of six. ten and five respect- 

 ively. ( )thers are so complex that no single formula can 

 describe them. Opium, for example, is a constituent in 

 the poppy, and opium consists of carbon, hydrogen, 

 oxygen and nitrogen. But let opium feel the touch of 

 the analyst, and it at once breaks into numerous simpler 



