1835.] Calico- Printing. 173 



excess of lime. In a few hours the indigo is deoxidized 

 and dissolved. The new products, peroxide of iron and sul- 

 phate of lime, are allowed to subside, and a clear yellow 

 coloured solution of indigo remains. When a piece of cloth 

 is dipped in this solution the yellow indigo immediately 

 quits the lime to deposit itself upon the fibres of the cloth. 

 When the cloth is exposed to the air the indigo soon recovers 

 its oxygen and becomes blue. 



The indigo solution has a yellow colour, but its surface is 

 always blue ; or, if very strong, copper coloured, from the 

 oxidizement of the indigo by the contact of air. Acids 

 throw down from it white indigo ; while those metallic 

 oxides that readily part with their oxygen throw down the 

 indigo in a blue state. This is the case with the sesqui- 

 oxide and binoxide of manganese, the salts of copper and 

 its blue hydrate. And these substances are taken advantage 

 of by the printer to produce various effects upon his calicoes. 

 In the specimen before us oxide of copper has been employed 

 to prevent the indigo in the blue vat from attaching itself 

 to particular parts of the cloth. For this purpose a solution 

 of the sulphate or acetate of copper made into a paste with 

 flour or pipe-clay and gum-senegal, is printed upon the 

 white cloth, and when dry, the whole is immersed in the 

 blue vat. The indigo becomes-fixed upon those parts of the 

 cloth where no paste has been applied ; but, on the surface 

 of the paste it is arrested by the copper, which, by yielding 

 oxygen, renders the indigo blue and insoluble before it can 

 reach the cotton. A little of the copper remains after wash- 

 ing, which is taken away by means of sulphuric acid. 

 (To be continued.) 



Article II. 



Researches into the Number of Suicides and Murders committed 

 in Russia in 1821-22. By M. C. T. Hermann, [read 1832 

 and 1833.] {Peter sburgh Memoirs, ii. 257.) 



The results detailed in this paper were procured from the 

 governors of the different provinces. The population, 

 according to the returns derived from them, of the pro- 

 vinces collectively, was in 1820, 39,030,072; and in 1827, 

 39,572,633. Since 1812 the increase of the population has 

 been very rapid. . For the seven years alluded to, the increase 



