CHEMICAL SCIENCE. 239 



(added to the residue in the crucible) must also consist of 25 cwt. of 

 lead and 42 Ibs. of zinc. The cause of the unavoidable result of the 

 process attempted by the author lios in the necessity for stirring the 

 melted metals. The oxidation of the lead and zinc at the surface of 

 the mass is very disadvantageous. 



The argentiferous zinc obtained by this process always retains a 

 portion of lead sufficient for the refining of the silver after the zinc 

 has been separated from the mixture ; and the alloy of silver and lead 

 remains in the distillation muffle. If the percentage of lead is not 

 sufficient for this purpose, more must be added, in order that in the 

 distillation vessels the silver may be acccumulated in the lead, which 

 is afterwards cupelled. The distillation does not present any difficul- 

 ties when suitable muffles are employed. The author had muffles 

 constructed, which, except a slit f of an inch in diameter, were quite 

 closed for a height of 4 inches from the bottom. The slit could be closed 

 and re-opened in the usual manner, when the distillation being com- 

 pleted it was necessary to draw on the remaining argentiferous lead. 

 Such a muffle was charged for each distillation with 1 cwt. of the 

 alloy of zinc, lead, and silver. The product of four distillations of a 

 mixture which, according to the most careful essays, contained 47 

 ozs. of silver, was 242 Ibs. of lead and 44 9-44 of silver. The loss of 

 silver amounted, therefore, to 3 1-22 oz. ; this is owing chiefly to the 

 scattering of small globules in the muffle, and it partly remains in 

 the scum, from which it may be again recovered by subsequent 

 distillations, washings, &c. 



OX THE ACTION OF SUGAR UPON IRON. 



At the British Association, Mr. Gladstone drew attention to the 

 fact that the owners of iron-built vessels object to sugar cargoes, on ac- 

 count of the rusting of the metal by the saccharine juices that exude 

 from the casks ; and this had led to a chemical examination of the re- 

 action then instituted. It was found that when pieces of iron were 

 placed in bottles containing a solution of cane sugar, the metal at the 

 edge of the liquid soon became deeply corroded, but that which was per- 

 manently immersed in the fluid remained bright for a considerable time. 

 The solution soon gave indications of the presence of protoxide of 

 iron, which absorbing oxygen from the atmosphere was speedily thrown 

 down as the red sesqui-oxide, leaving the sugar free to dissolve a fresh 

 quantity of iron, the precipitated oxide in the mean time forming a 

 deposit. After eighteen months, the liquid was of a deep red-brown 

 color ; it became pale blue with ferrocyanide of potassium, black with 

 sulphuret of ammonium ; alkalies produced no precipitate ; nitric acid 

 peroxidized it. A portion dried and analyzed gave 20.78 parts 

 of metallic oxide to 100 of combined sugar, which is almost exactly in 

 the proportion expressed by the formula C 12 H u O n , FeO. The au- 

 thor, however, considered that this might differ from the true composi- 

 tion by one equivalent of water. No such iron compound could be 

 formed by direct combination. In vain was it attempted to dissolve 



