256 PROCEEDINGS OF THE AMERICAN ACADEMY 



if a sufficiency of oxygen were admitted to burn the most richly hy- 

 drogenized body known, it may generally be well to admit enough for 

 such a case. 



The volume of oxygen actually consumed in burning the lightest 

 liquid known — probably of the formula Cg Hk, — which I have 

 separated from petroleum, and which contains a larger percentage of 

 hydrogen than any other non-gaseous body, as compared with the 

 volume of carbonic acid formed, is as 1.62 : 1 ; the fraction representing 

 the oxygen which is taken up by the hydrogen of the body, and which 

 of course becomes condensed and disappears from the volume of car- 

 bonic acid. In burning this body with just the equivalent quantity of 

 oxygen, — assuming that the combustion would be complete under such 

 cireumstances, — we should have one bubble or volume of carbonic acid 

 entering the potash bulbs for every 1.62 bubbles or volumes of oxygen 

 entering the sulphuric acid bulbs. A sufficient excess of oxygen would 

 be secured in this case, and a simple ratio obtained, if 2 bubbles of 

 oxygen were to be admitted for 1 bubble of carbonic acid appearing in 

 the potash bulbs. The case would then be further simplified by having 

 the openings in the sulphuric acid bulbs of such size as would give 

 bubbles twice as large as those from the potash bulbs ; as then, when 

 the bubbling should be equally rapid in both, the relation between 

 the volumes of the gases would still be maintained, viz. 2 vols, of 

 oxygen to 1 vol. of carbonic acid. Such bulbs would be highly desira- 

 ble, but would probably have to be made expressly for the purpose. 



4. As an additional control over the supply of oxygen, and serving 

 also as a temporary safeguard against the escape of incompletely ox- 

 idized substance, in case of too rapid distillation, with an insufficient flow 

 of oxygen, I have two or three inches in length of the tube filled with 

 coarse, strongly ignited oxide of copper, placed in front of the asbestos, 

 and this followed by a plug of the latter substance to keep it in place, 

 and prevent the formation of a channel along the upper surface of the 

 oxide of copper. The tube itself being laid in an iron trough, as above 

 described, with the upper half of the tube exposed, the oxide of copper 

 is heated in such a manner that any reduction would be readily ob- 

 served at the end in contact with the asbestos. In this manner it 

 serves as a valuable indicator, by which to determine, at a glance, 

 whether the flow of oxygen is sufficient. It will rarely happen that 

 any reduction of the oxide of copper will take place. I have, however, 

 in some of my earlier experiments, with too short a column of asbestos. 



