M. TECHNOLOGY. 551 



used, but the sulphethylic acid mixes perfectly uniformly with 

 them. The green turbidity that soon appears after a while 

 becomes black, and, after standing twenty-four to forty-eight 

 hours, forms a slight black sediment. Poppy and rape oils 

 become perfectly clear ; linseed-oil in thick layers retains a 

 trace of yellow. The oils, after being drawn off from the 

 sediment, must be thoroughly shaken with several quarts of 

 hot water, to free them from traces of sulphuric acid, and then 

 be allowed to settle. 9 C^ December^ 1871, 186. 



SIDEEIX-YELLOW. 



The addition of a hot, saturated solution of bichromate of 

 potash to a neutral solution of sesquichloride of iron produces, 

 after heating for some time, a fine yellow precipitate of a basic 

 chromate of sesquioxide of iron of definite constitution, which, 

 when washed and dried, may be used, under the name of sid- 

 erin-yellow, as a pigment, free from lead, and unafiected by 

 light and the atmosphere. This is not only suitable for an 

 aquarelle and rapidly drying oil color, but, when intimately 

 ground with water-glass, it forms a coating that dries rapidly, 

 and hardens like cement into a stony incrustation, which run- 

 ning water does not afiect. With ultramarine it gives a green 

 pigment of similar properties. The following proportions are 

 based npon the chemical reactions which take place in the 

 preparation : Crystallized sesquichloride of iron, 433 parts, 

 and bichromate of potash, 1473 parts. After a long boiling 

 of these constituents together in water, 378 parts of the basic 

 chromate of the sesquioxide of iron, or siderin-yellow, separate, 

 while 90 parts of water of crystallization are liberated from 

 the sesquichloride of iron, and 1049 parts of chromochloride 

 of potassium remain in the aqueous solution, with 389 parts 

 of chromate of potash. ^13 C^N'ovemher 1, 1872, 1432. 



GRENADE, A NEW DYE-STUFF. 



A secondary product of the manufacture of fuchsine, em- 

 ployed for some time in dyeing woolen goods, under the names 

 of cerise, aniline, orseille, etc., has of late contained impurities 

 in the form of insoluble foreiorn substances, which has suofsrest- 

 ed the effort to render it sufiiciently pure to warrant its use 

 with the finer fabrics. A dye-stuff*, named grenade, has been 

 produced at the factory of Knosp, in Stuttgart, which is said 



