Chemistry and Physics. 237 



taining 9*5 per cent of methane is the most readily explosive. 

 The combustion is complete so long as the methane does not fal 

 below 5-5 per cent. Even with 4*5 per cent slight explosion 

 were noticed. With 12 per cent of methane, the explosibility 

 reaches its maximum limit, no explosion having ever been obtained 

 when the proportion was as high as 12*25 per cent. 



In a subsequent paper, the authors state that if the current by 

 which the wire is heated be shunted with a parallel wire, the pro- 

 duction of the spark causes no ignition of the gas, if the resist- 

 ances are equal in the two branches. If the shunt-resistance is 

 high, or on the other hand if this resistance falls below a certain 

 value, the production of a spark always produces an explosion. 

 To avoid an explosion therefore the current strength must not 

 exceed a certain maximum depending on the resistance of the two 

 branches of the conductor. — C. R., cxxvi, 750, 901, March, 1898. 



G. F. B. 



6. On a Crystallized Compound of Cuprous Chloride and 

 Acetylene. — It has been pointed out by Chavastelon that on 

 treating cuprous acetylide with hydrochloric acid in the cold, an 

 appreciable evolution of gas takes place ; due probably to the 

 decomposition on warming of a compound of cuprous chloride 

 and acetylene. Further investigation showed that this compound 

 may be prepared either by the action of acetylene on a solution 

 of cupric chloride in alcohol or in water, in presence of metallic 

 copper, or by passing this gas into a saturated solution of cuprous 

 chloride in dilute hydrochloric acid, at a temperature at or below 

 12°. By the latter method, which is preferable, large hexagonal 

 crystals are obtained belonging to the orthorhombic system, hav- 

 ing the composition C 2 H 2 : Cu 2 Cl 2 . By the former process, silky 

 crystals are yielded, which are liable to contamination by a violet- 

 purple deposit, formed early in the reaction. Both products alter 

 readily on exposure to the air, and are at once decomposed by 

 water or by solutions of alkali chlorides, with evolution of acety- 

 lene and the production of the above mentioned violet-purple sub- 

 stance. The crystals dissociate on warming without explosion, 

 producing at 78° a pressure of 262 cm .— C R., cxxvi, 1810-1812, 

 June, 1898. G. f. b. 



7. Matter, Energy, Force and Work, A plain presentation of 

 Fundamental Physical Concepts and of the Vortex-atom and 

 other Theories. By Silas W. Holman, Professor of Physics 

 (Emeritus) Mass. Institute of Technology. 12 mo, pp. xiv, 257. 

 New York, 1898 (The Macmillan Co.). — The aim of this book, as 

 the preface tells us, is to present some fundamental ideas and defi- 

 nitions of physics in a plain and logical manner. The subject 

 matter proper is contained in the first part, the definitions and 

 views there given constituting "a sporadic attempt at clear con- 

 secutive setting forth of individual thought." The second part 

 consists of speculations on matter and energy. Two new terms 

 are introduced, Mnergety and weighted. Kinergety in the abstract 

 sense denotes " the idea of capacity for kinetic energy " and in 

 the concrete sense "the quantity of this capacity." Weightal is 



