PKOGEESS IN EXPLOSIVES GUTTMANN. 293 



artificial silk is not fully dried, but from 12 to 30 per cent of water 

 is allowed to remain in it. 



For the sake of completeness mention must be made of the pro- 

 posed use of explosives for motive power. I well remember having 

 shown me at Vienna, in 1878, an engine to be Avorked by small charges 

 of dynamite. In order to shoAv the absence of danger the inventor 

 had made the model entirely of wood. Again, quite recently my 

 advice was sought regarding the application of smokeless powder to 

 flying machines. Several patents referring to motors and com- 

 pressors driven b}' explosives have been taken out, and one of them 

 quite recently." 



An account of progress on explosives would be incomplete without 

 mention of the conditions under which they are manufactured. 



The late Col. Sir Vivian Dering Majendie deserves lasting recogni- 

 tion for having created that most excellent explosives act of 1875. 

 The influence of this act, and perhaps almost to the same extent of the 

 annual reports of the British inspectors of explosives on the arrange- 

 ments and construction of buildings and machinery, the general clean- 

 liness of the operations performed, and the security of workmen 

 against accident can hardly be overrated, and the example set in this 

 country has been followed all over the world. 



In arranging buildings due consideration is now paid to the dan- 

 gers present on account of the nature of the operation and the quan- 

 tit}^ of materials dealt with. The advent of high explosives has 

 unfortunately made us acquainted with effects of explosions unknoAvn 

 in the old powder days, and in order to counteract these effects the 

 author recently suggested ^ the construction of danger buildings in a 

 special kind of ferro-concrete. The buildings are so designed that 

 pieces of burning debris can not penetrate their roofs, and so bring 

 about their destruction. At the same time the shock of the exj^losion 

 transmitted from a distance through the ground Avill not cause the 

 walls to open out. This proposal has been very favorably received 

 by a number of manufacturers, and in several instances has already 

 been adopted. The armoring of such a building forms a Faraday's 

 cage, and renders the whole structure lightning proof. This is of 

 importance, since the regulations governing the erection of lightning 

 conductors have not increased the safety of buildings to any great 

 extent in spite of lightning-rod conferences and investigations. Mag- 

 azines which were satisfactorily tested on the very day of a thunder- 

 storm have been blown up, and nothing short of a cage, or at least a 



« British patexits, Nos. 961, of 1874 ; 24742, of 1904 ; 28376, of 1904 ; 22J 25, of 

 1905. 



* " Explosions and the Building of Ejfplosives Works," Journal of the Society 

 of Chemical Industry, 1908, No. 13. 



