552 THE POPULAR SCIENCE MONTHLY. 



new discoveries, still rules. The " muriatic radicle " gave Lavoisier 

 some trouble, for lie could find no oxygen in muriatic acid, and 

 his experiments upon it with oxygen resulted in the production 

 of a neutral substance which must be its calx ; and so he called 

 chlorine oxidized muriatic acid. Such mistakes were natural in 

 the early days of chemistry. The decomposition of volatile alkali, 

 or ammonia, by Berthollet, led to the suggestion which Lavoisier 

 gave out with great modesty, that many earths, still regarded as 

 simple, might be compound ; and that their apparent indifference 

 to oxygen should be attributed to their being already saturated 

 with it. 



On the nature of gases and vapors, which had not been under- 

 stood before, Lavoisier asserted, in a memoir published in 1777, 

 that most bodies were capable of existing in three different states 

 — those of solids, liquids, and vapors, or aeriform fluids. The 

 terms airs, vapors, and aeriform fluids express only a single form 

 of matter — a class of bodies infinitely extended ; and this principle 

 " gives the key to nearly all the phenomena relative to the differ- 

 ent kinds of air and to vaporization." "While heat tends to change 

 volatile bodies into vapor, the pressure of the air has a contrary 

 effect; and "the tendency of volatile bodies to evaporate is in 

 direct ratio to the heat to which they are exposed, and inverse to 

 the weight or pressure brought to bear upon them." Lavoisier's 

 memoirs on heat, expansion and contraction under changes of 

 temperature, and latent heat, show an insight into the accepted 

 principles. He discussed with much sagacity the question 

 whether heat is a fluid or a force ; and it would not be hard, for 

 one who is determined to look for it, to find in his essays on this 

 subject a prevision of the current constitutional chemistry. La- 

 voisier's later labors were physiological. They include papers on 

 the production of carbonic acid in respiration and the office of the 

 lungs in the process, in which the present theory is proposed as a 

 secondary hypothesis, and on cutaneous transpiration. In his 

 physiological studies, M. Dumas has found that he had arrived 

 at a remarkable anticipation of modern views concerning the re- 

 lations of organic to inorganic nature. 



Lavoisier carried his energy into several other fields, and made 

 his mark in all. He cultivated an estate of two hundred and forty 

 arpents in the Vendome, and in nine years doubled its production. 

 His name is associated with a number of propositions looking to 

 the public welfare or economical reform. In 1789 he presented in 

 the National Assembly a report of the " Caisse d'Escompte," to 

 which he had been attached for one year. As commissioner of 

 the treasury he proposed in 1789 a new plan for the collection of 

 imposts, which he elaborated in a special essay entitled " The Ter- 

 ritorial Wealth of the Kingdom of France," a work which, accord- 



