J. M. Ordway — Waterglass. 475 



tate is formed which, if the heating is not Jong continued, is 

 mostly or wholly redissolved on cooling. This precipitation 

 must be due to the lithium constituent, since sodium water- 

 glass alone is not so affected. Could the deposit then be a 

 simple lithium silicate ? 



In making quantitative trials with respect to this matter it is, 

 of course, necessary to keep up the heat till the curd is 

 removed from the solvent action of the mother liquor. There- 

 fore the dish holding the liquid, the stirring stick, the press 

 cloth and frame, the draining dish and the press boards were 

 heated together in an oven kept at the desired temperature. 

 While still in the hot space the curd was transferred to the 

 cloth and drained and the folded cloth was placed between the 

 boards. These were then quickly withdrawn from the oven 

 and subjected to strong pressure. 



1. 37 g. of a solution containing 19 p. c. of 2(Li 2 - 3Si0 2 ) + 

 Na„O2Si0„ were heated to 80° C. The cake was transparent 

 and weighed a little over one gram and had 49 p. c. of 

 Li 2 0-3Si0 2 -|-Na 2 (>3Si0 2 . It dissolved readily in cold water. 



8. 85 g. of the same solution heated to 90° C. yielded 6 - 5 g. 

 of transparent cake containing 58 p. c. of 5(Li 2 O3Si0„) + 

 2(Na 2 O3Si0„). This dissolved completely in three times its 

 weight of water. 24 p. c. of the solid matter had been thrown 

 down. 



So this lithium constituent imparts its thermic character to 

 its associate and the two refuse to part company. 



It seemed barely possible that mixed monosilicates with the 

 lithium element largely predominant might be made to yield a 

 pure lithium silicate by fractional crystallization. 



9a. 56 g. of a 13 p. c. solution of Na 2 O4Si0„ with 60 g. of a 7 

 p. c. solution of LiHO produced a coagulum which soon redis- 

 solved. A dish holding the clear solution was put under a bell 

 glass with two dishes of calcium chloride in lumps. In four 

 weeks, the temperature ranging sometimes as high as 40° C, the 

 weight was reduced to 21 g. In this residue were some bits of 

 an apparently crystalline crust amounting to nearly two grams. 

 These were perfectly soluble and consisted of 7(Li o - Si0 2 '4H„0) + 

 Na 2 0'Si0 , 4H 2 0. The rest was a somewhat pasty mass of opaque 

 amorphous matter. 



From what has been detailed so far it may fairly be inferred 

 that the clean dissociation of double silicates cannot be brought 

 about by any mode of treatment. 



After the discovery of the peculiar effect of heat on lithium- 

 bearing silicates, the way was clear to attempt the formation of 

 a simple hyclrated lithium silicate by direct synthesis. The 

 union must be effected without the use of heat. 



