170 



SCIENCE 



N. S. Vol. XXX. No. 762 



tion ; a process which has an important in- 

 fluence in the filling of metalliferous veins. 

 Eesearches of this class are being continued, 

 and should lead in time to useful conclu- 

 sions. 



One research, outside of the normal work 

 of the survey, was carried out by Dr. H. N. 

 Stokes in the survey laboratory. I refer to 

 his remarkable investigation of nitrogen 

 chlorophosphide.^^ From this supposedly 

 well-known compound, PsNgCle, Dr. Stokes 

 developed a series of polymeric bodies, 

 P,N,Cls, P5N5CI10, PeNeCl,2 and P,N,C1,,. 

 Each of these yielded its own characteristic 

 phosphimic acids, and other derivatives, 

 and thus a new field of study in inorganic 

 chemistry has been opened, which deserves 

 to be carefully cultivated in the future. 



From what has been said so far it is clear 

 that the chemical work of the Geological 

 Survey is not limited by utilitarian consid- 

 erations, but is also distinctly scientific in 

 its aims. It was felt that the investigations 

 of the geologists could be aided fully as 

 much by chemical researches as by mere 

 routine analyses, and the results obtained 

 seem to justify this supposition. As a fur- 

 ther help to geology, the more important 

 data of geochemistry have recently been 

 brought together in the form of a large 

 bulletin,^" in which the carefully verified 

 bibliographic references are quite as useful 

 as the text. Furthermore, the chemical 

 work has been carried on in close relations 

 with various physical researches, among 

 which the studies by Carl Barus of the iron 

 carburets, the thermoelectric measurement 

 of high temperatures, and the behavior of 

 fused rocks as electrolytes are conspicuous. 

 At present, under G. F. Becker, the subject 

 of elasticity is being investigated, with ref- 

 erence to some of the larger problems of 

 geophysics. Physics and chemistry are in 



"Bull. 167, U. S. Geol. Survey, p. 77. 



-' " The Data of Geochemistry," by F. W. Clarke. 

 Bull. 3.30 of the U. S. Geological Survey, 1908. 



contact at so many points that applications 

 of the one inevitably compel consideration 

 of the other. 



There is, however, a natural call for data 

 of immediate economic significance ; and to 

 meet this demand some special laboratories 

 have been recently organized. In 1904, at 

 the St. Louis Exposition, the Geological 

 Survey established a coal-testing plant, in 

 which a great number of coals were studied 

 from various technical points of view. 

 From this enterprise the technologic branch 

 of the survey was developed and in it a 

 variety of chemical investigations are now 

 being conducted. Coals, including lignites 

 and also peat, are collected and sampled in 

 large lots, and analyzed both proximately 

 and ultimately. Their calorific value is 

 directly measured, their availability for 

 briquetting or for the manufacture of pro- 

 ducer gas is studied, and certain problems 

 which arise in mining operations are also 

 taken into account. For instance, the gases 

 evolved from coal within the mine are care- 

 fully examined, and the explosives used by 

 the miners are investigated also. At pres- 

 ent the prevention of mine explosions is 

 receiving special attention; and one labo- 

 ratory is devoted to that subject alone. In 

 another laboratory the proximate constitu- 

 ents of coal are being isolated, with a view 

 to ascertaining their true character. Work 

 of this kind is evidently capable of indefi- 

 nite extension, and how far it may ulti- 

 mately go it is impossible to foretell. 



Another group of investigations, which 

 is partly chemical, relates to the manufac- 

 ture and properties of cement, and its use 

 as a structural material. Clays, limestones 

 and finished cements are subjected to an- 

 alysis, and the question of their durability 

 under special conditions is also studied. 

 The government of the United States is 

 engaged in the reclamation of great areas 

 of arid lands, and is constructing large 



