224 ANNUAL OF SCIENTIFIC DISCOVERT. 



bath is as follows : The patient is plunged to the neck into a metallic bath 

 isolated from the ground, and is seated with the legs horizontal on a wooden 

 bench of the whole length of the body, which is also isolated from the bath. 

 The water is acidulated with nitric or hydrochloric acid for the extraction of 

 mercury, silver, or gold, and with sulphuric acid for lead. The patient being 

 in the bath, one end of the bath is put in contact with the negative pole of the 

 battery by means of a binding screw, and he is made to take the positive pole 

 sometimes in the right and sometimes in the left hand. The arm is sustained 

 by means of supports in connection with the bench. The patient being thus 

 placed, the current enters the body, circulates from the head to the foot, and 

 is neutralized on the sides of the bath at the negative pole. Being isolated 

 from direct contact with the negative pole, his body radiates in the bath the 

 electricity which forms in it, a multitude of currents issuing from the entire 

 surface, after having traversed the internal organs, and even the bones, to be 

 neutralized on the negative side of the bath. 



ON THE ELECTRO-CHEMICAL TREATMENT OF ORES OF SILVER, 

 LEAD, AND COPPER, BY M. BECQUEREL. 



This electro-chemical process consists in preparing the ores hi such a man- 

 ner that the resulting compounds of silver and lead (in operating upon galena) 

 may be soluble in a saturated solution of common salt ; these compounds are 

 chloride of silver and sulphate of lead. "When the solution is made it is put 

 into a wooden reservoir, when the decomposition of the metallic salts is ef- 

 fected with couples formed of plates of zinc and tinned iron, or copper, of 

 masses of calcined charcoal, or even of plates of lead and the same negative 

 elements. The plates of zinc or lead are placed in bays of sail-cloth filled 

 with a saturated solution of salt, which are immersed in the metallic solution ; 

 the other plates are put into the latter, and the communication established 

 between them by means of wires. "With plates of zinc a deposit of very fine 

 particles of all the reducible metals is obtained on the negative plates. "With 

 lead plates the deposit consists of silver in greater or less purity, according to 

 "the proportion of lead in the solution. Wooden boxes, steamed for the re- 

 moval of all extractive substances, are better than the sail-cloth bays ; or 

 porous earthen vessels may be employed, filled with fragments of amalgamated 

 zinc and mercury. The action is then more regular, and 'the quantity of zinc 

 consumed is in atomic proportion with that of the deposited metals. By 

 varying the constitution of the voltaic couples, each of the metals contained hi 

 the solution may be successively separated. 



This process has been tried on a large scale, and is stated to be especially 

 applicable to the working- of silver ores, not only in the case of the positive 

 want of mercury, but even when the price of that metal becomes rather high. 

 Abridged from the Comptes Rewlvs, June, p. 1095, Chemical Gazette, No. 



'. 



