78 Intelligence and Miscellaneous Articles. 



added to it ; the capsule being again covered, the heat is to be con- 

 tinued till vapour ceases to appear ; the glass plate must then be re- 

 moved and replaced by folds of blotting-paper, the heat being con- 

 tinued in the bath, until a glass rod being immersed in the capsule, 

 it becomes covered, on removing it, with yellow, solid chloride of 

 gold. 



The capsule is then to be removed from the salt-water bath, and 

 the chloride of gold soon crystallizes in small prismatic crystals, of 

 a fine yellow colour, with an orange tint. The chloride thus obtained 

 is perfectly soluble in water without reduction ; it is successfully em- 

 ployed in Daguerreotype and other operations. 



The red chloride of gold (terchloride) is prepared in the same 

 manner, except that the aqua regia employed is prepared with two 

 parts of hydrochloric and one part of nitric acid. The operation is 

 commenced by acting upon gold with excess of aqua regia on a sand 

 bath, the salt water bath not being used until the gold is entirelj' 

 dissolved ; the remainder of the operation is conducted in the same 

 manner as that for the yellow chloride. — Journ. de Ph. et de Ch., 

 Mai 1844. 



ON BRESILIN AND BRESILEIN. BY M. PREISSER. 



Bresilin is the colouring matter of Brazil, Fernambuc or Nicara- 

 gua wood ; this colouring principle was discovered by M. Chevreul, 

 who obtained it by treating Brazd wood with alcohol, in the same 

 manner as he obtained hematin from logwood. 



This process, however, M. Preisser states, yields only an impure 

 product ; he procured it by acting on the interior and slightly co- 

 loured part of Brazil wood, in a state of great purity. 



The properties of bresilin are like those of Ixematoxylin, recently 

 isolated by Erdmann ; it exists in small colourless needles, which 

 appear to be rectangular prisms. Its taste is sweet, with a slightlv 

 bitter after-taste. It is soluble in water, and the solution may be 

 long kept without alteration ; it becomes coloured only on the edges, 

 of a lively red colour. By boiling the colouring takes place much 

 more rapidly ; the liquor becomes of a fine crimson-red colour, and 

 if this red coloured liquid is evaporated, it deposits numerous satin- 

 like crystals of a bright and very fine red colour. 



M. Preisser gives the name of bresilein to bresilin coloured of a bright 

 red. Bresilin is soluble in alcohol and in aether ; with the contact 

 of air it is coloured bright red by means of hydrochloric acid ; sul- 

 phuric acid dissolves it, renders it yellow and soon blackens it. Di- 

 lute nitric acid reddens it very strongly ; if the mixture be heated, 

 red vapours are disengaged and oxalic acid is produced. 



The action of chromic acid and the alkaline chromates is very re- 

 markable, and it is the more important to insist upon this action, as 

 it explains numerous important applications in calico printing. 



As soon as chromic acid or bichromate of potash in fine powder is 

 added to a concentrated solution of bresilin, brisk effervescence ensues, 

 and by distillation the liquor yields a notable quantity of formic acid ; 

 the liquor becoming of a deep brown colour, and after some hours a 

 deep crimson lake separates. This lake is formed of the modified 



