ELISHA MITCHELL SCIENTIFIC SOCIETY. 15 
cently close to show that the substances examined were 
practically the same. 
On concentrating the liquid poured off from the green 
gum, it was repeatedly observed that more of the gum 
was obtained. Fer instance, in the experiment described 
where the green mass from fifteen grams weighed about 
eight grams, a further portion weighing 0.3915 gram was 
gotten. The analysis of this yielded the following per- 
centages : Cr, 13.66; K, 8.57; and SO,, 55.45. Wecounld 
only regard this as a mixture consisting in part of the 
green basic mass which had not completely separated 
out. The small amount of material left in solution (less 
than one-half gram) consisted of a little chromium with 
sulphuric acid in the ratio of about five to one. 
Next the action on chromium sulphate was examined. 
The chromium sulphate used was in the form of small 
violet scales or crystals. It was a commercial product 
and the method of its preparation was unknown to us. 
An analysis of it gave: 
Tei is therefore a basic chromate, but we have seen no 
such body described in the books. It dissolved in water 
with a green color. Fifteen grams of this disselved in 100 
cc. of water, boiled to a concentration of 50 cc. and pre- 
cipitated with 100 cc. of alcohol, yielded about ten grams 
of the green, gummy mass, very similar in appearance to 
that obtained from the alum, but more soluble in alcohol. 
In a second experiment twelve grams were taken and 
treated in the same way, and yielded about eight grams. 
The analysis showed these to be identical. 
Calculated for Found. 
Cro (SO4)3.Cre(OH)¢.15H, 0. ye II. III. 
ie is is 4g wee OO 22.41 * 22-40 22.69 
3 OS etter Penhe 33.17 34.64 34.73 34.43 
Wareei to. 0S 550% 43.77 iy PS ae 
The agreement is far from satisfactory, but the body 
is evidently a basic salt. oe 
