1835.] the Advancement of Science. 203 



and the other with the gas to be experimented on, were 

 attached to one of the arms, and two thermometers, the 

 one with a moist bulb, and the other dry, were introduced 

 into the other leg. The bladder was then pressed, and the 

 air forced through the acid. It passed over the thermo- 

 meters, and gave the temperature of the gas at the dew 

 point. This enabled the value of a to be determined, or the 

 specific heat. A correction was made for the impurity of 

 the gas, which was transmitted over mercury and analysed. 

 Most of the experiments corresponded with those of the 

 French chemists, except in one or two instances. The 

 general result obtained was, that under equal weights, the 

 gases have the same specific heat ; and, under equal vo- 

 lumes, the specific heat is proportional to the specific gra- 

 vity, except with hydrogen, which, under equal volumes, 

 has double the specific heat. 



The results are represented in the following table : — 



18. Dr. Dalton introduced the subject of a system of che- 

 mical symbols, by explaining his ideas respecting the com- 

 position of the simple compounds, and exhibited the expres- 

 sions which he proposed many years ago, to give a pictorial 

 view of the mode in which the atoms are collocated. He 

 consid'ers the composition of nitrous oxide to be 2atoms azote, 

 adopted by Berzelius, who has not stated from whom he 

 obtained it. defiant gas, he considers, is composed of 

 single atoms of carbon and hydrogen, while the gas which 

 exists in coal, though commonly termed olefiant gas, is, in 

 reality, double olefiant gas, and is termed by Dr. Dalton, 

 bin-olefiant gas. This is proved by its affording twice the 

 quantity of carbonic acid, and requiring twice the quantity 

 of oxygen, to burn it, which olefiant gas requires. 



Mr. Whewell observed that the atoms might as well be 



