J. M. Ordway on Waterglass. 181 
nitely soluble in water. Both are precipitated by alcohol sti 
partial decomposition, and indeed in both the acid and base se 
to be in astate of association rather than of strict chemical Kenic 
eae The following experiments, illustrating this point, 
may be compared with the similar trials of silicates mentioned 
in Part III: 
20. 350 g. of a solution gree 6 p. c. of KSn,.,, were mixed with 
850 c. c. of aleohol of sp. gr. 0°840. After we washings with alcohol, 
the floceulent precipitate v was voollestia in a cloth and hard pr The 
thin translucent, brittle cake, after twelve hours exposure to the a 
ghed 24 g. ad contained 82 p. ¢. of nz4. It was dissolved in 
parts of water and treated with alcohol re before. The second ce 
when ered and aired contained & 1 p. e. of KSn,.,. The third 
cipitation showed 81 p. c. of KBn The fifth precipitate contained 82 
P. ¢. 0 ee a And ES sate ‘product was readily soluble in water 
and showed 72 p. ¢. of 
- 50 g. of pressed erytle ‘of stannate of potash were dissolved in 
water, so as to make 600 ¢.c. 200 cc. of 5-4 p.c. nitric acid were 
stirred j in, and, when the liquor “had recovered its transparency, 1700 ¢. c. 
of alcohol were added. After one washing with alcohol the pultaceous 
precipitate was very gradually squeezed and then ha essed. r 
some 9 urs exposure — the air, the cake weighed 27 g. and contained 79 
p.c. of KSn,.,. It was dissolved in 9 times its weight of water and 
treated with alcohol. “The second flocculent deposit hard pressed and 
ed in the air, contained 80 p.c. of KSn,s- The precipitation was re- 
many times, and finally the tenth pre weighing 5:5 g» was 
the small insoluble residue had nearly roy same composition 
Metastannate of potash is also. thrown down as sack by many 
potas h salts; and here too, as with waterglass, the acetate and 
the chlorid prove most efficient. 
22. 25 g. of a solution ang 21 p.¢. of KBn,., were mixed with 
25 g. of a 20 p- c. KCI solution. “The very bulky deposit after being 
Squeezed and subjected to oa pressure, weighed 674 g. It contained 28 
< é vt mother liquor and 64 p. ¢. of KSn,.;, and was readily soluble in 
; os 40 g. of a 9 p.c. solution of KSn,.7 mixed with 40 g. of a 10 
_ P+ ¢. solution of acetate of potash gave & precipitate that compressed we 2. 
aie ee contained 68 p.c. of KSn,.,. This was wholly soluble in 
_ Carbonate pape peeing B or nitrate of potash gine — 
Precipi time 
a In whatever quantity, has no effect upon a metastan =. 
- . account of the insolubility of metastannate of soda, soda. 
ae t$ soon disturb a solution of metastannate of potash. ‘Thus: 
