CHEMISTRY: RICHARDS AND DAVIS 
57 
Thus 1.0000 g. of napthalene in burning was capable of raising our 
calorimetric system by 3.616° and 1.0000 g. of toluene 3.821°, (or 1.0567 
times as much as the same weight of napthalene) both substances hav- 
ing been weighed in air. According to the careful absolute determina- 
tion of the Bureau of Standards 1 g. of naphtalene thus weighed evolves 
9622 calories (20°) on burning. Hence 1 g. of toluene must evolve 10,168 
calories, the toluene being weighed in air. Corrected to vacuum and 
to 18° this would become 10,158, a value only slightly less than that 
(10,166) found by Richards and Barry. A part at least of the differ- 
ence may be due to the different standard of reference used in this 
case (napthalene instead of sugar). Evidently, the combustiopLS in 
the earlier Harvard research must have been essentially complete, for 
such difference as exists is in the direction opposite from that which 
would have been caused by incompleteness of combustion. 
Both results are much higher than that found by Roth and Auwers,^^ 
who apparently did not test the residual gases for carbon monoxide 
after combustion, and found the gram of toluene to give only 1.0529 
times as much heat of combustion as a gram of napthalene, instead of 
1.0567. It is not impossible that either all our toluene contained a slight 
aliphatic impurity^^ (a rather unlikely contingency because we obtained 
samples from various sources) or theirs contained traces of some other 
contamination, — since it is so very difhcult to purify completely a com- 
pound of carbon, even by countless distillations, from substances with 
nearly the same boiling point. 
Many other determinations of a variety of organic substances have 
been made here with the help of these improved methods and the mat- 
ter will be pursued further, with especial reference to purity of materials. 
The results will be conmiunicated in the near future in a publication 
of the Carnegie Institution of Washington, to which we are much in- 
debted for generous assistance in this work. 
Summary. — In this paper there are described improvements in various 
details of the procedure of calorimetric combustion, to wit: means of 
effectively closing the bomb with less risk of injury to the platinum lining 
and cover; means of burning volatile liquids without loss; a method of 
automatically controlling the temperature of the environment about 
the calorimeter so as to make the calorimetric operation more conven- 
ient and more truly adiabatic; and means of evaluating the incomplete- 
ness of combustion, if any volatile carbon compounds should remain 
unburned. New determinations of the heat of combustion of toluene 
are recorded, giving the value 10,155 calories (18°) per gram (weighed 
in vacuo). This is but a preliminary pubHcation. 
