572 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Preparation of Perchloric Acid. — For this purpose H. 

 IT. Willard employs ammonium perchlorate, a comparatively 

 inexpensive salt. He decomposes this by boiling its solution 

 with aqua regia, evaporates off the excess of the latter and thus 

 obtains the perchloric acid. The yield is theoretical, since the 

 perchloric acid takes no part in the destruction of the ammonia. 

 By the use of pure materials the acid may be thus obtained in a 

 pure condition, but the author recommends the distillation of 

 the acid at a pressure of about 100 min , and gives details in regard 

 to the apparatus. The acid obtained either by evaporation or 

 by subsequent distillation corresponds nearly to the formula 

 HC10 4 .2H 3 0. 



An interesting matter in connection with this work on the prep- 

 aration of perchloric acid is the study which the author has 

 made concerning the destruction of ammonia by aqua regia. 

 He has found that chlorine gas alone when passed into the boil- 

 ing solution has little effect, but that nitrous acid is the active 

 agent, as was shown by the fact that nitric acid and a reducing 

 agent, such as formic acid, would destroy the ammonium salt. 

 The most unexpected result was the fact that the gas given off 

 by the action of aqua regia upon an ammonium salt is chiefly 

 nitrous oxide, N 2 0. The prevailing opinion that nitrogen gas is 

 the principal product under these circumstances must now be 

 abandoned as erroneous. — Jour. Amer. Chem. Soc, xxxiv, 1480. 



H. L. W. 



2. Centenary Celebration of the First Commercial Gas Com- 

 pany. Edited and Published by the American Gas Institute. 

 8vo, pp. 174. New York, 1912 (29 West 39th st., New York 

 City). — This book contains the lectures delivered at the celebra- 

 tion, held in April, 1912, at the Franklin Institute in Philadelphia, 

 of the centenary of the event of the first commercial sale of gas 

 as an illuminant. An interesting chronology of the early devel- 

 opment of gas lighting, as well as a description of a loan exhibi- 

 tion of historical objects relating to the industry is included. 

 The lectures are on by-products of gas manufacture by Professor 

 Charles E. Monroe, on the commercial aspects of the gas indus- 

 try by Hon. George B. Cortelyou, on the technique of gas manu- 

 facture by Alfred E. Forstall, on gas as an illuminant by Van 

 Rensselaer Lansingh, and on the use of gas for heat and power, 

 and on the testing of gas by E. B. Rosa. h. t.. w. 



3. The Analyst's Laboratory Companion ; by Alfred E. 

 Johnson. 12mo, pp. 164, Philadelphia, 1912 (P. Blakiston's 

 Son & Co.). — This American issue of a British book is a collec- 



