OXYGEN AND THE NATURE OF ACIDS. 123 



nitrous air being received by two measures of this without any increase 

 of dimensions. Now as common air takes about one half of its bulk 

 of nitrous air before it begins to receive any addition to its dimensions 

 from more nitrous air, and this air took more than four half measures 

 before it ceased to be diminished by more nitrous air, and even five half 

 measures made no addition to its original dimensions, I conclude that it 

 was between four and five times as good as common air. It will be seen 

 that I have since procured air better than this, even between five and six 

 times as good as the best common air that I have ever met with. 



MEMOIR ON THE EXISTENCE OF AIR IN THE ACID OF NITRE 

 (AND ON THE MEANS OF DECOMPOSING AND RECOM- 



POSING THIS ACID).* 



I 



By ANTOINE-LAURENT LAVOISIER. 



TOOK a small retort with a long narrow neck, which I bent over a 

 lamp so that the end of the neck could be held under a bell-jar full 

 of water standing in a vessel of water. Into the retort I put two ounces 

 of slightly fuming acid of nitre, the weight of which was to that of dis- 

 tilled water in the proportion of 131,607 to 100,000. I added two ounces 

 one dram of mercury and heated it slightly to hasten the solution. 



As the acid was very strong, the effervescence was lively and the de- 

 composition very rapid. I received the air which was liberated in differ- 

 ent bell-jars in order to be able to tell the differences which might be 

 found between the air at the beginning and at the end of effervescence, 

 supposing there should be such. When the effervescence had stopped 

 and all the mercury had dissolved, I continued to heat the material in 

 the same apparatus. Soon boiling appeared in place of the effervescence, 

 aud while the boiling went on air was produced in almost as great 

 abundance as before. I continued this until all the fluid had passed 

 out, either by distillation or as elastic vapors of air, and nothing was left 

 in my retort save a white salt of mercury, in a pasty form, dry rather 

 than wet, which began to grow yellow on its surface. The quantity of 

 air obtained up to this point was about 190 cubic inches; that is to say, 

 about four quarts. All this air was of a uniform sort and was nowise 

 different from what M. Priestley has called nitrous air. 



On continuing the experiment, I noticed that from the mercury salt 

 there arose red fumes like those of the acid of nitre; but this phenom- 

 enon did not last long and soon the air in the empty part of the retort 



* Read before the Paris Academy of Science on April 20, 1776. Translated for The Popular 

 Science Monthly from the ' Comptes Rendus ' for the meeting. 



