650 Professor Dewar [June 11, 



more particularly iuto the presence of water in such bodies, and the 

 source of the nitrogen found in the same. 



Since the above analyses of different graphites were made, a 

 sample of the artificial graphite which results from the action of 

 oxidising agents on the cyanogen compounds present in crude caustic 

 soda has been examined. The following analysis shows that this 

 artificial variety of graphite is characterised by giving a very large 

 yield of marsh-gas. 



CO2 45-42 



CO 39-88 



CH- 4-43 



H 8-31 



N 2-00 



Occluded gases in volumes of the graphite = 53-13. 



Meteorites, no doubt, have an exceedingly low temperature before 

 they enter the earth's atmosphere, and the question had been raised 

 as to what chemical reactions could take place under such conditions. 

 It resulted from Professor Dewar's investigations that at a tem- 

 perature of about — 130° C. liquid oxygen had no chemical action 

 upon hydrogen, potassium, sodium, phosphorus, hydriodic acid, or 

 sulphydric acid. It would appear, therefore, that as the absolute 

 zero is approached even the strongest chemical affinities are inactive. 



The lecturer exhibited at work the apparatus by which he had 

 recently succeeded in solidifying oxygen. The apparatus is illustrated 

 in the accompanying diagram,* where a copper tube is seen passing 

 through a vessel kept constantly full of ether and solid carbonic acid ; 

 ethylene is sent through this tube, and is liquefied by the intense 

 cold ; it is then conveyed by the tube, through an indiarubber stopper, 

 into the interior lower vessel ; the outer one is filled with ether and 

 solid carbonic acid. A continuous copper tube, about 45 feet long, 

 conveying oxygen, passes first through the outer vessel, and then 

 through that containing the liquid ethylene ; the latter evaporates 

 through the space between the two vessels, and thus intense cold is 

 produced, whereby oxygen is liquefied in the tube to the extent occa- 

 sionally of 22 cubic centimetres at one time. The temperature at 

 which this is effected is about — 180° C, at a pressure of 75 atmo- 

 spheres, but less pressure will suffice. When the oxygen is known to 

 be liquid, by means of a gauge near the oxygen inlet, the valve A is 

 opened, and the liquid oxygen rushes into a vacuum in the central 

 glass tube below ; some liquid ethylene at the bottom of the next 

 tube outwards is also caused to evaporate into a vacuum at the same 

 moment, and iustantly some of the liquid oxygen in the central tube 

 becomes solid, owing to the intense cold of the double evaporation. 



♦ This illustration appeared in 'Industries' of July IG, 1886, and is kindly 

 lent by the proprietors. 



