72 



SCIENCE. 



[N. S. Vol. IX. No. 211. 



aiul acetylene continues to attract much atten- 

 tion. Ten French factories are now making cal- 

 cium earbid and four more are being built, and it 

 is said two French villages are lighted wholly by 

 acetylene gas, at a cost of 50 per cent, less than 

 coal gas. On the other hand, Welsbach is mak- 

 ing improvements in his burner, and Nernst 

 gives hope of a yet more brilliant and econom- 

 ical source of light, as has already been de- 

 scribed in the columns of Science. In conclu- 

 sion. Dr. McMurtrie says: "In every direction 

 industrial progress is suggestive, and we may 

 expect advancement in all directions with in- 

 creasing intensity. Commercial artificial indigo, 

 commercial artificial silk, commercial mercer- 

 ized cotton in its various forms, the new colors 

 and medicinal substances from carbon com- 

 pounds, new concentrated nutritive substances, 

 synthetic albumen, the various toxins and ex- 

 tracts of animal matters of therapeutic value, all 

 claim a large share of attention ; and so do 

 hundreds of other substances and processes in 

 which the principles of chemistry find applica- 

 tion to human needs." 



In the Italian Oazetta RebufFat contributes an 

 exhaustive study of hydraulic cements. These 

 he divides into two classes : (1) amorphous, 

 compact cements, which consist of lime, calci- 

 um orthosilicate and calcium aluminate, in 

 which, however, the free lime may be wanting ; 

 this class contains the hydraulic limes and quick 

 settling cements. (2) Crystalline cements, con- 

 sisting of a crystalline compound of calcium 

 orthosilicate and lime, with a varying quantity 

 of calcium aluminate ; this class contains Port- 

 land cements and those rich in silica. After 

 hardening, however, all these cements have the 

 same qualitative composition, consisting of a 

 mixture of calcium hydrate, hydrated calcium 

 silicate of the formula 2(SiO^, 2CaO),H,0, and 

 hydrated calcium aluminate, with a small 

 amount of inert matter. In cements rich in 

 silica a small amount of a double silicate of 

 calcium and aluminum is present, which ac- 

 counts for the resistance of these cements to 

 sea water. The hardening of cements is chiefly 

 due to the hydrating of the calcium silicate, 

 and to a lesser degree to the hydrating of the 

 calcium aluminate. 



In a recent English patent Weil and Levy 

 claim to electroplate aluminum in baths to 

 which various organic substances are added. 

 Thus for the deposition of silver, hydroquinol 

 is added to an ammoniacal cyanid solution ; for 

 copper, ammonium gallate or pyrogallate is 

 used; for nickel, milk sugar, and the same for 

 gold. 



J. L. H. 



CUBBENT NOTES ON METEOBOLOGY. 



CLIMATE AND HYGIENE OF THE CONGO FEBE 

 STATE. 



An important volume on the climate, soil and 

 hygiene of the Congo Free State has been issued 

 as the second part of the Proceedings of the Con- 

 gres National d'Hygiine et de CUmatologie MSdi- 

 cale de la Belgiqiie et du Congo, held in Brussels, 

 August 9-14, 1897. The investigation, of which 

 the results are embodied in this report, was 

 undertaken by a commission of the Societe royale 

 de Medicine puMique et de Topographie medicate 

 de Belgiqiie. On this commission meteorology 

 was represented by M. Lancaster, Director of 

 the Meteorological Service of Belgium, which is 

 equivalent to saying that whatever concerns 

 meteorology and climatology in this report is 

 admirably done. As a whole, this volume gives 

 us the most complete and most scientific account 

 of the meteorology and medical climatology of 

 this interesting district that has yet appeared. 

 The first chapter, of 404 pages, is devoted to 

 the meteorology,' and presents a careful sum- 

 mary of what is known concerning the at- 

 mospheric conditions and phenomena of the re 

 gion, including many tables and diagrams. 

 This portion of Africa is one of great interest 

 to meteorologists on account of the seasonal 

 migration of the belt of equatorial rains, and 

 the data concerning the rainfall at Vivl and 

 other stations are, therefore, especially wel- 

 come. Chapter II., of twenty pages, is de- 

 voted to the geology and soil conditions. Over 

 400 pages are concerned with the naedical cli- 

 matology and hygiene of the region in general 

 and of the different stations in particular. This 

 last chapter is an extremely valuable one. Of 

 especial interest at the present time is the evi- 

 dence afforded (p. 464-5) by the result of 

 European colonization in the Congo Free State 



