708 
Proceedings of the Royal Society of Edinburgh. [Sess. 
XLIY. — Combustion Analysis. By J ames Walker, F.R.S., and Thomas 
Blackadder, B.Sc., University College, Dundee. 
(MS. received July 6, 1908. Read same date.) 
The process of Dennstedt for the elementary analysis of organic com- 
pounds by combustion in oxygen with the help of platinised quartz was 
tried in this laboratory, and in expert hands was found to be both rapid 
and accurate. The average student, however, experienced great difficulty 
in the conduct of the combustion, and it occurred to us that the advantages 
of the apparatus of Dennstedt, so carefully worked out by him in detail, 
might be applied to the ordinary method of combustion by means of copper 
oxide. 
If one inspects a tube in which a copper oxide combustion is being 
conducted, it is found that the oxide actually reduced to metallic copper, 
after the combustion of the volatile matter is completed, rarely extends for 
more than an inch or two along the tube, unless the process has been 
accidentally “rushed.” It seemed, therefore, possible to reduce the 
dimensions of the combustion tube to such an extent as to secure the 
advantage of the Dennstedt furnace, which from its lightness of construc- 
tion admits of rapid heating and cooling. This we discovered to be the 
case, and in reality there is no greater difficulty in performing a copper 
oxide combustion in a shortened Dennstedt furnace, heated by three Bunsen 
burners, than in a furnace of the customary type heated by thirty. The 
saving of initial outlay on the furnace, and on the current consumption 
of gas is, of course, comparatively great, but a still more considerable 
advantage is that the combustion may be done on the worker’s bench 
without inconvenience to himself or to his neighbours. 
The furnace employed by us, together with the burners, absorption- 
tubes, and the purifying apparatus for the supply of oxygen, are practically 
all as described by Dennstedt, and shown to scale in fig. 1. The chief 
modification is that the furnace is cut down to 60 cm. in length. The 
combustion tube is of Jena glass, 66 cm. long, and need not be more than 
8 mm. internal diameter. The total volume of such a tube is only about 
30 c.c., and the charge of copper oxide, including spirals, weighs only 35 g. 
Two of the burners are supplied with attachments for spreading the flame 
into a flat sheet : the third is used for local heating, but towards the end 
