646 Dr. J. Emerson Reynolds [May 28, 



prolonged action of water on ordinary chloroform at high tempera- 

 tures. The latter can afford formic acid along with hydrochloric acid. 

 Silicon chloroform affords precisely similar products at ordinary tem- 

 peratures, but the soluble silico-formic acid immediately changes into 

 the anhydride, and that is the white insoluble substance which has 

 separated in the tube before you. This change may be represented 

 thus : — 



2(HSiOOH) = i|o>^ + H^O 



Silico-Formic Acid. Anhydride. 



Again, both silicon and carbon form gaseous compounds with 

 hydrogen of similar composition : — 



CH4 and 8iH4 



Neither of these hydrides can be obtained by direct union of the 

 respective elements, though they are easily obtained by indirect 

 means, with the details of wliich I need not trouble you. Both are 

 colourless gases as you see. The carbon hydride, or marsh gas, is 

 combustible, but requires to have its temperature raised considerably 

 before it takes fire in air, and its flame is only slightly luminous. It 

 produces on complete oxidation water vapour and caribou dioxide gas. 

 The analogous silicon hydride takes fire much uKjre easily in air, and 

 when not quite pure is even spontaneously combustible under 

 ordinary conditions, and it bnrns producing water vapour and solid 

 silicon dioxide. 



" Silico-Organic Chemistry." 



Now, just as marsh gas may be regarded as the starting point of 

 that great branch of science which is usually spoken of as Organic 

 Chemistry, so the analogous hydride of silicon is the primary com- 

 pound from which many substances which are often termed silico- 

 organic compounds can be derived by various means, and these were 

 discovered in the course of the classical researches of Friedel, 

 Crafts, Ladenburg and others. 



I wish to avoid using many chemical formulae, which probably 

 would convey but little meaning to some of those whom I address ; 

 it will suffice to merely indicate the lines on which investigations 

 have proceeded in this direction. 



In the older work of Friedel, Crafts and Ladenburg, they 

 produced complex substances by the substitution of various radicles 

 (always carbon groups), for one atom of hydrogen in SiH4, and 

 ultimately replaced another atom of hydrogen by the OH or hydroxy 1 

 group. The substances so fonned were silicon alcohols which may be 



