258 An BJfay on Bleaching. 



they might break in confequence of the heat produced hf 

 the union of the acid in water. In fome places thefe pro- 

 portions vary. In England, the following are ufed : 



Manganefe 30 parts. 



Common fait - 80 



Sulphuric acid - 60 



Water - 120 



Such is the ley employed at Manchefter, where nothing is 

 bleached but cotton cloth, and cotton and thread. 

 In Ireland, the proportions are : 



Manganefe 60 parts. 



Salt 60 



Sulphuric acid - 50 



Water 50 



This is the common ley of tho'fe who bleach linen cloth; 

 and hence we may explain the great difference between thefe 

 and the preceding proportions. 



In Germany the dofes vary a little, and approach near to 

 the proportions ufed in the French manufactories. They are: 



Manganefe 20 parts. 



Salt - - 64 



Acid - 44 



Water 54 



The neceffity of diftilling this acid on a large fcale, has 

 given rife to the invention of different kinds of apparatus 

 more or lefs convenient. Berthollet has propofed matraffes 

 with bent tubes, which convey the oxygenated muriatic acid 

 to the pneumatic tub, in which the bubbles, traverflng the 

 water, are forced, by means of an agitator, to combine more 

 or lefs with it. Pajot de Charmes recommends the ufe of 

 tubulated retorts; but, befides thefe veflels being too dear, 

 they do not anfwer the propofed end, fince a portion of ful- 

 phuric acid not decomnofed, and which injures the procefs, 

 always paffes into the water. 



C, Widmer, at Jouy, has arranged his apparatus in fuch 

 a manner as to lofe the lea(t gaspotlible during the condenfa- 

 tion : he receives the gas under a capfule inverted at the bot- 

 tom of the apparatus; above thefe are two tours de goutiere 

 alfo inverted, their another capfule above thefe; then two 

 more tours de goutiere, and then another capfule, which ter- 

 minates the apparatus. The difpofition of his tub is fuch, 

 that he places around in his laboratory feveral diftilling ap- 

 paratuses, which are going at the fame time. 



Apparatuses conftrucled on Similar principles are alfo in 

 ufe at Glafgow and Manchefler. JBourboulon-de-Bonneuil 

 has likewife invented an apparatus, confiding of feveral ma- 

 traffes, 



