Chemical Science. 441 



25. Colouration of Gold. — The following mixtures are recom- 

 mended by M. Castelluni, for this pnrpose :— Water, 150 parts; 

 muriatic acid, of s])ecific gravity, 1.18, 10 parts ; oil of vitriol, 4 parts; 

 crystallized boracic acid, 2 parts. 



A second mixture consists of 150 parts of water ; 13 parts of a 

 solution ofacidmuriate of alumina; 4 parts of crystallized sulphate 

 of soda ; and 3 parts of crystallized boracic acid. To each of these 

 mixtures should be added 20 grains of a neutral solution of mu- 

 riate of gold. 



26. On the Absorbent Powers of Salts for Water. — ^The following 

 results have been obtained by M. Brandes. The substances after 

 being dried, even by a red heat, when they would bear it, were then 

 placed in the atmosphere of a close vessel containing a little water. 



Carbonate of potash — 100 parts absorbed 360.3 of water in 42 

 days ; the solution itself is hygrometric; but the power varies with 

 the state of the atmosphere. 



Sulphate of potash — 100 parts, heated for half an hour, lost 1.25 

 parts, and regained them immediately in a moist atmosphere. 



Bitartrate of potash — 100 became 96 by drying, and then 100.2 

 in the moist atmosphere. 



Tartrate of potash — 100 absorbed 82.3 of water in 53 days, and 

 became liquid. 



Acetate of potash — 100 absorbed 91.1 in 4 days, and became 

 liquid. 



Sulphate of soda — 100 became 41 by drying; then absorbed 

 54.6 in 36 days. 



Phosphate of soda — 100 lost 63 by drying; the rest absorbed 65 

 in 21 days. 



Nitrate of soda — 100 absorbed 80 in 220 days, and became 

 liquid. 



Borax — 50 parts lost 18 by calcination; the rest absorbed 41 in 

 130 days. 



Acetate of soda — 100 lost 39.2 by heat ; the rest absorbed 64.2 

 in 38 days. 



Rochelle salt — 100 dried became 82.5 ; these absorbed 26.75 in 

 8 days. 



Chloride of Calcium — 100 absorbed 124 in 96 days; the whole 

 was liquid on the 4th day. 



Sulphate of Magnesia — 100 gave 57 by heat; these absorbed 

 44.68 in 83 days. 



Alum — 100 lost 42.9 by heat ; the rest absorbed 46.5 in 25 days. 



Sulphate of Copper — 50 parts absorbed 17.35 in 62 days. 



Verdigris — 100 became 74.5 by drying; these absorbed 30 in 

 12 days. 



Crystallized Chloride of Antimony — 50 parts absorbed 55 in 70 

 days. 



Emetic Tartar-^bO lost 1 by heat; the 49 absorbed 1.5 of water 

 in 18 hours. 



