Experiments with Explosives 241 



of carnivora, herbivora, and insectivora. Mr. Thiselton- 

 Dyer remarked that some vegetable types showed a tendency 

 to assume forms characteristic of very different orders. 

 For example, the genus Senecio includes many adaptive 

 types, such as tree-like, succulent, and climbing forms. 



June iSth, 397th meeting. Mr. d'Abbadie 1 (guest) drew 

 attention to the nature of hazes, by which, even in the -driest 

 atmosphere, the sun is often obscured and mountains, at 

 a distance of three or four miles, are invisible. Though so 

 common as to have received a special name in the languages 

 and dialects of many savage tribes, their true nature has not 

 been fully studied, nor their origin determined. He also gave 

 some account of his scientific travels, especially on magnetic 

 surveys in Africa and Arabia. 



1892. June i6th, 4o6th meeting. Captain Noble gave 

 an account of some experiments on explosives. It was 

 generally agreed that for artillery the pressure employed 

 should not exceed 17 tons per square inch. The maximum 

 pressure with the new explosive compounds did not exceed 

 that of the old, but in some cases, and especially with 

 cordite, fifty per cent, more energy was imparted to the 

 projectile, the pressure on the interior part of the gun being 

 increased, but not that on the chamber. The results given 

 by the old gauge were incorrect, because the products of 

 explosion were forced into the gauge. It \vas not advan- 

 tageous to increase the velocity of the projectile above 

 2000 feet per second, though one of 3000 feet might be 

 obtained. Owing to the resistance of the air a better result 

 is got by increasing the weight of the projectile. He men- 

 tioned that cordite of large diameter is blown from a gun 

 imperfectly burnt, the residue being cordite in all respects 

 similar to the newly-prepared material. 



Oct. 27th, 407th meeting. Mr. Crookes said that a study 

 of the phosphorescent spectrum of yttrium had suggested 

 that it was really a compound. Progress had been made 



1 A. T. d'Abbadie (1810-1897) lived in Paris and studied meteorological 

 and astronomical subjects, writing on these and on earthquakes, shooting 

 stars, and gravitation. 



P.C. Q 



