August 1, 1864.] THE TECHNOLOGIST. 



ON CHEMISTRY APPLIED TO THE ARTS. 21 



processes. It is first thoroughly washed, treated by steam to remove all 

 viscous substances, then a weak solution of alkali is allowed to percolate 

 through the char, which removes saline matters and a certain amount 

 of colouring matter, when it is further acted upon by weak hydrochloric 

 acid, which in removing a certain amount of the lime salts liberates the 

 colouring matters ; the char is again washed with weak alkali to remove 

 the remaining colouring matter, and lastly the decol orating power of the 

 black is restored by passing through it a solution of bi-phosphate of lime. 

 It is to be hoped that the high praise bestowed upon this process on the 

 Continent may induce our manufacturers to try it, as they would obtain 

 two strict advantages by its use. First, the economy of operating at 

 once upon the black and restoring its properties without removing it 

 from the cylinders. Secondly, the prevention of the noxious odours 

 given off during the revivification of char by the ordinary methods. It 

 is interesting to note one of the results of the different employment of 

 char in this country and on the continent. In England the wear and 

 tear in sugar refinery is constantly repaired by the introduction of fresh 

 char, and there is no spent or old char for sale. In France, on the con- 

 trary, owing to the great impurities in their beet-root sugar syrups, and 

 to the use of blood in refinery, the char becomes rapidly clogged with 

 organic matter, and is so completely animalised, that its value as a 

 manure exceeds what the char originally cost the refiner. The result is 

 that French " spent " char is annually exported to the French colonies 

 to the amount of 120,000 tons, and is there used as a manure to promote 

 the growth of the sugar cane. So important is this article of commerce 

 considered, that the French Government have appointed special analy- 

 tical chemists to determine its value for the trade. 



Phosphorus. — I am now about to call your attention to one of the 

 most marvellous and valuable substances ever discovered by chemists. 

 In 1660, Brandt, a merchant of Hamburgh, discovered a process for ob- 

 taining phosphorus from putrid urine ; but though he kept his secret, a 

 chemist named Kunckel published the mode of obtaining it from this 

 fluid. A hundred years later, Gahn discovered the presence of phos- 

 phorus in bones ; and Scheele shortly afterwards gave a process to 

 obtain it therefrom. The process devised by this eminent chemist was 

 shortly afterwards improved upon by Nicolas and Pelletier, and their i 

 method was so completely worked out by Fourcroy and Vauquelin, that 

 it is still the process used in the present day. The preparation of phos- 

 phorus consists of four distinct operations — 1st, 80 parts of thoroughly 

 calcined and pulverised bones are mixed with 80 parts of sulphuric acid, 

 sp. gr. 1*52, to which is then added 400 parts of boiling water ; 2ndly, 

 after a few days the clear liquor, containing bi-phosphate of lime, is re- 

 moved from the insoluble sulphate, and evaporated until it has the 

 specific gravity of l - 5 ; 3rdly, this liquor is mixed with 20 per cent, of 

 finely pulverised charcoal, and the whole is dried at a moderately high 

 heat, when, 4thly, it is introduced into an earthenware retort, placed in 



