ELISHA MITCHELL SCIENTIFIC SOCIETY 58 
In the case of this solution (1) the crystals which first form- 
ed were found to contain a good deal of carbon dioxide. It 
was evident that the solution had not been exactly neutralized 
by the sodium carbonate but that an excess had been used. 
With successive crops the amount of carbon dioxide decreased 
and of chromium increased. Although the analysis of the 
third and fourth crops approached nearly to that of the double 
chromate reported by Zehenter, traces of carbon doxide were 
found throughout, and so another solution was prepared and 
more carefully neutralized. But the evident crystallizing to- 
gether of the chromate and carbonate raised the question as 
to the possible formation of a body of exact composition con- 
taining these two. In the case of solution (1) the first crop of 
crystals was practically all chromate and the seventh and later 
crops again strongly carbonate. In solution (7) when potas- 
sium chromate and potassium carbonate were mixed several 
crops of crystals were gotten, the first being almost pure chro- 
mate and the latter carbonate, the two showing little tendency 
to crystallize together. 
In solution (2) the 3rd crop of crystals gave 27.45 percent. 
iee., 4th crop, 2810; 5th crop, 27:15; 6th crop, 28,03. ‘There 
was a failure in this case also to prepare crystals of defi- 
nite composition. 
From solution (3) three crops of very deliquescent 
brown crystals were gotten which corresponded in com- 
_ position to the formulas 2Na,CrO,.(NH,),.CrO,.4H,O. 
From solution (4) crop (a) coanica to be a mixture, 
yielding nothing definite ; crop (b) consisted of crystals of 
NaNH,CrO,,. 2H, ,O ; crops (c) and (d) gave sodium chro- 
mate, we .CrO,,4H20, differing from the ordinary chromate 
with ten molecules of water. 
Solution (5) yielded first potassium bichromate and 
then a large number of crops of large flat hexagonal crys- 
tals which had the composition 3K,CrO,.Na,CrO, 
Solution (6) yielded no new compound, the two bichro- 
mates crystallizing out separately. 
Solution (8) yielded a large number of crops of 
the double chromate of potassium and magnesium 
K,CrO,. MgCr0,.2H,0. 
