A double Sulphate of Guanidine and Aluminium. 
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A Double Sulphate of Guanidine and Aluminium. By F. 
Ferraboschi, B.A., Clare College. 
[. Read 9 March 1908.] 
In the course of some experiments upon the preparation of 
alums and other double salts of various organic bases, solutions of 
guanidine carbonate, aluminium sulphate, and sulphuric acid 
were mixed together approximately in the proportions that would 
be required for the formation of an alum. The solution was left 
to evaporate, and in the course of two days some crystals made 
their appearance. As these did not appear, from their shape, to 
be crystals of an alum, I undertook, at Dr Fenton’s suggestion, an 
analysis of the substance with a view to ascertaining its com- 
position. 
It was found that both the guanidine and the aluminium had 
entered into its composition. 
A quantitative analysis was then made with the result that it 
was found to possess the formula 
(CN 3 H 5 ) 2 H 2 S0 4 . Al 2 (S0 4 ) 3 . 12H 2 0, 
or CN 3 H 5 . HA1 (S0 4 ) 2 . 6H 2 0. 
The figures obtained were as follows : — 
Experiment I. Determination of aluminium. 
A weighed quantity of the substance was heated to a bright 
red heat in a platinum crucible until its weight became constant, 
and only alumina remained ; 
Weight of substance T9853 g. 
Weight of A1 2 0 3 '2645 g. 
Experiment II. Determination of sulphate ion. 
This was precipitated and weighed as BaS0 4 ; 
Weight of substance ’5611 g. 
Weight of BaS0 4 ’6741 g. 
Experiment III. Determination of nitrogen. 
This was done by Dumas’ method, the nitrogen evolved being 
collected and measured over 1 in 2 potash ; 
Weight of substance •3410 g. 
Volume of nitrogen obtained 32 5 c.c. 
Temp. 18° C. 
Bar. 759 1 mm. 
Pressure of aqueous vapour over 1 in 2 potash at 18°, 7 7 mm.; 
whence, 
Weight of nitrogen ‘0378 g. 
