Apeil 17, 1896.] 



SOIENGK 



605 



their economical production was dependent on 

 the invention of mechanical mixers applied 

 in other arts. In a historical resum6 the 

 recency of most of the inventions and dis- 

 coveries was pointed out, and it was shown 

 how large a proportion was due to Ameri- 

 can scientific men. The many smokeless pow- 

 ders manufactured or proposed were enum- 

 erated and classified into mixtures of diSerent 

 cellulose nitrates with oxidizing agents; mix- 

 tures of soluble or insoluble cellulose nitrates 

 with nitro-glycerine; mixtures of cellulose ni- 

 trates with nitro-substitution compounds; and. 

 pure cellulose nitrate powders, and the methods 

 of manufacture were briefly described. 



The author's own experience in inventing a 

 smokeless powder was then given. Recogniz- 

 ing at the outset the necessity for the closest 

 approximation to absolute chemical and physical 

 uniformity in a high-powered powder, and being 

 familiar with the diificulty of securing such 

 constancy in a physical mixture, he set about 

 producing a powder from a carefully purified 

 cellulose nitrate of the highest degree of nitra- 

 tion. This was the first and only attempt, so 

 far as the lecturer was aware, to produce a 

 powder which consisted of a single substance 

 in its pure state. 



The powder was manufactured at the Torpedo 

 Station and proved at Indian Head by ordnance 

 ofiicers of the Navy. Secretary Tracy in his re- 

 port (1892) says: "It became apparent to the 

 Department, early in this administration, that 

 unless it was content to fall behind the standard 

 of military and naval progress abroad in respect 

 to powder, it must take some steps to develop 

 and to provide for the manufacture, in this 

 country, of the new smokeless powder, from 

 which extraordinary results had been obtained 

 in Europe. With this object negotiations were 

 at first attempted looking to the acquisition of 

 tlie secret of its composition and manufacture. 

 Finding itself unable to accomplish this, the 

 Department turned its attention to the develop- 

 ment of a similar product from independent 

 investigation. The history of these investiga- 

 tions and of the successful work performed in 

 this direction at the Torpedo Station has been 

 recited in previous reports. It is a gratifying 

 fact to be able to show that what we could not 



obtain through the assistance of others we suc- 

 ceeded in accomplishing ourselves, and that the 

 results are considerably in advance of those 

 hitherto obtained in foreign countries." 



The conditions that smokeless powder should 

 fulfill, and the tests prescribed by the lecturer 

 were then set forth, and in closing he pointed 

 out that the powder was now developed to a 

 higher degree than the gun and that changes 

 in the latter to render it more efficient were 

 being considered by ordinance experts. 



A. C. Peale, 



Secretary. 



GEOLOGICAL SOCIETY OF WASHINGTON, 

 MAECH 25, 1896. 



Mr. Whitman Cross described the diorite of 

 Ophir Loop, Colorado, and the remarkable in- 

 clusions contained in it. The diorite at this 

 locality is a lateral arm of a stock which cuts 

 up through Cretaceous sedimentary rocks and 

 a bedded volcanic series of Tertiary andesites. 

 The lateral offshoot from this stock is intruded 

 as an irregular sheet between the Dakota Cre- 

 taceous and the upper Jurassic, reaching a thick- 

 ness of 1,000 feet. In its lower portion it is 

 locally very full of included rock fragments. 

 These inclusions were described, and specimens 

 were exhibited. They are interpreted as gene- 

 tically connected with each other and with the 

 diorite magma, which brought them to their 

 present position. 



The diorite is a variable rock, with augite 

 and hornblende. The inclusions vary from felds- 

 pathic rocks, poor in dark silicates, to black 

 amphibolites nearly free from feldspar. They 

 are developed in granular and banded forms, 

 and exhibit all manner of gradations in struc- 

 ture as well as in composition. 



The study of these rocks led to the stated con- 

 clusions that quite local differentiation has gone 

 on in the depths from which both diorite magma 

 and inclusions came, and further, that a shear- 

 ing movement of the difierentiated magma, fol- 

 lowed by consolidation, produced rocks greatly 

 resembling many gneisses, amphibolites and 

 schists, and especially those of the Archean 

 complex. It was suggested that some gneisses 

 and associated rocks of unexplained or assumed 

 metamorphic origin may be primarily banded 



