1832.] Proceedings of Societies. 255 



water. The fused mass in the crucible, also, on solution yields a copious yellow 

 precipitate with acetate of lead ; but the operation requires to be repeated several 

 times before complete decomposition of the ore takes place. 



The crystallized bichromate of potash, made by Mr. Heath, appears to be per- 

 fectly pure, and would be sure of a market in Europe. It is this substance which, 

 is used for dyeing. A short description of the process is given in Ure's translation 

 of " Berthollet's Arts of Dyeing." All shades of orange and yellow may be produ- 

 ced by adding to the solution of the salt, acids or alkalies ; the acids rendering the 

 color deeper, and the alkalies, lighter. The mordant generally used is sugar of 

 lead. The salts of mercury may also be employed, but they are more expensive." 

 Mr. Heath recommends the bichromate as suitable for the dyeing of Choppahs, Ban- 

 dannoes, &c. Cotton twist however would be dyed much cheaper at the place 

 where the dye was extracted from the chromate of iron, as in this way the process 

 of crystallization would be rendered unnecessary. Mr. Heath has, in anticipation of 

 a demand for this new, product, established an extensive apparatus for its manu- 

 facture, and another for the manufacture of acetic acid, so as to enable him to 

 supply the sugar of lead at the cheapest rate. 



Chrome yellow, or chromate of lead, is much used as a pigment, but it has 

 hitherto borne a very high price. America and Russia have furnished the 

 greater part of the European supply : the Americans prepare it with saltpetre 

 taken from this country, and chromate of iron from Baltimore and New Jersey* 

 an ore by no means so pure as that discovered in Salem. It is natural to expect 

 therefore that all the preparations of chrome will soon be advantageously export- 

 ed from India. 



The chrome yellow might find a market in China and the Burmese empire, as 

 a substitute for the yellow sulphuret of arsenic, now extensively employed in the 

 ornamental work of the lacquered-ware. 



2. — Medical and Physical Society, 

 2nd June, 1832. 

 Messrs. D. McLeod, J. Stokes, S. Ludlow and O. Wray, proposed at the last 

 Meeting, were elected Members of the Society ; and Drs. Blest and Passaman, 

 of Chili, were elected Corresponding Members. 



Cloquet's Quarto Work on Anatomy, and Manec's Plate of the Cerebro-Spinal 

 Nerves recently received, were placed on the table ; also Specimens of Chulchulera, 

 (lichen,) forwarded by Dr. Falconer. 

 The following communications were then laid before the Society : 



1. A letter from Mr. Cope, stating, that in proceeding up the Ganges to 

 Dinapore, he had met with a species of Argemone ; the A. Mexicana, the seeds 

 of which contain a large proportion of fixed oil ; and he observes, that prior to 

 his leaving England, a quantity of oil of the A. Mexicana, the produce of the 

 West Indies, had been used in London as a mild purgative. Mr. Cope wishes to 

 bring this subject before the notice of the Society, in hopes that the plant may 

 afford an useful addition to the Materia Medica of India. 



2. A letter from Superintending Surgeon G. Playfair, to the Medical Board, 

 containing a brief notice of an Epidemic Influenza that had appeared at Merut, on 

 the 7th April ; and in the course of 10 days, affected above 200 men of H. M. 

 26th Foot. The disease was marked by violent catarrhal symptoms, and pains in 

 the back and limbs. The Epidemic appeared at Bareilly early in April, but no 

 instance of a fatal termination was known. 



