478 Scientific Intelligence. 



evidence of it being the effect produced by the issuing gas on 

 solution of baryta. At about 40° to 50° above this slow com- 

 bustion temperature, the burning becomes rapid and a distinct 

 flame is visible. The eight different specimens examined gave 

 results as follows: yellowish-brown carbonado burned at 690° 

 with flame; black carbonado at 7lO°-720° with flame; trans- 

 parent Brazilian diamond at 7GO°-770° without a flame; cut 

 diamond from the Cape, at 780°-790°, without a flame ; Brazilian 

 bort at 790° without a flame and at 840° with a flame; Cape bort 

 at 790° without a flame and at S40° with a flame; very hard bort 

 at 800° without and at 875° with a flame. The harder the 

 diamond as a rule the higher its point of ignition. Heated in 

 hydrogen to 1200° Cape diamonds do not lose weight, though 

 they may lose their transparency and become lighter in color. 

 At this temperature dry chlorine and dry hydrogen fluoride have 

 no action on them. The vapor of sulphur attacks them only at 

 1000°; but with carbonado, carbon disulphide is produced at 

 900°. The vapor of sodium has no action at 600°. Iron at its 

 fusing point attacks the diamond readily and graphite separates 

 on cooling. When heated with alkali carbonates at a high tem- 

 perature the diamond is rapidly dissolved with evolution of car- 

 bon monoxide but no hydrogen. Hence it cannot contain hydro- 

 carbons. — C. R., cxvi, 460, March, 1893. g. f. b. 



7. Oxygen in illuminating Gas. — While great attention is 

 being paid to the problem of transmitting energy by means of 

 electricity, the problems of accomplishing the same results by 

 means of compressed air and by gas are not being overlooked. In 

 the year 1890 Mr. Edward Tatham, of New South Wales, sug- 

 gested the addition of considerable quantities of pure oxygen to 

 warm heavy oil gas to produce a higher illuminating power. Dr. 

 L. T. Thorne later in the same year gave the results of some pre- 

 liminary experiments with such a gas — which were extremely 

 favorable. Preparations are being made at Huddersfield to pro- 

 duce this enriched gas on a large scale. It has been found that 

 the admixture of six per cent oxy-oil gas increases the illuminat- 

 ing power of the corporation gas by the equivalent of five and a 

 half candles. A marked increase is also noticed in the stability 

 of the gas under storage. The increased ^ost of production due 

 to such enrichment will not exceed a third of a penny per thou- 

 sand cubic feet. — JVature, Oct. 19, .1893. j. t. 



8. Refractive indices of Liquid Nitrogen and Air. — Professors 

 Liveing and Dewae have determined these constants by the 

 method of MM. Terquem and Trannin. This consists in suspend- 

 ing in the liquid whose iudex is to be determined, two plates of 

 glass with a thin layer of air between them and measuring the 

 angle of incidence at which the chosen ray suffers total reflexion 

 at the surface of the air. Professor Dewar found " that in a dou- 

 ble glass vessel of any form, where the outer and inner vessels are 

 separated by even narrow vacuous spaces, liquid oxygen can be kept 

 for a great length of time open to the air. Such a liquid, filtered. 



