12 FAMILIAR LETTERS ON CHEMISTRY. 



cost of bleaching to pay interest upon this capital, or to hire so much land in Eng- 

 land ! This expense would scarcely have been felt in Germany. Beside the dimin- 

 ished expense, the cotton stuffs bleached with chlorine, suffer less in the hands of 

 skilful workmen, than those bleached in the sun ; and already the peasantry in 

 some parts of Germany have adopted it, and find it advantageous. 



Another use to which cheap muriatic acid is applied, is the manufacture of glue 

 from bones. Bone contains from 30. to 36 per cent, of earthy matter chiefly phos- 

 phate of lime, and the remainder is gelatine. When bones are digested in mu- 

 riatic acid, they become transparent and flexible like leather, the earthy matter is 

 dissolved, and after the acid is all carefully washed away, pieces of glue, of the 

 same shape as the bones, remain, which are soluble in hot water and adapted to 

 all the purposes of ordinary glue, without further preparation. 



Another important application of sulphuric acid may be adduced, namely, to the 

 refining of silver, and the separation of gold, which is always present in some pro- 

 portion in native silver. Silver, as it is usually obtained from mines in Europe, 

 contains, in sixteen ounces, six to eight ounces of copper. When used by the 

 silversmith, or in coining, sixteen ounces must contain, in Germany thirteen ounces 

 of silver, in England about fourteen and a half. But this alloy is always made 

 artificially, by mixing pure silver with the due proportion of the copper ; and for 

 this purpose the silver must be obtained pure by the refiner. This he formerly 

 effected by amalgamation, or by roasting it with lead ; and the cost of this pro- 

 cess was about 21. for every hundred weight of silver. In the silver so prepared, 

 about T^W^ 1 * ysW tn P art f gld remained. To effect the separation of this by 

 nitric hydrochloric acid was more expensive than the value of the gold ; it was, 

 therefore, left in utensils, or circulated in coin, valueless. The copper, too, of the 

 native silver was of no use whatever. But the T^utta part of gold, being about 

 one and one half per cent, of the value of the silver, now covers the cost of refin- 

 ing, and affords an adequate profit to the refiner ; so that he effects the separation 

 of the copper, and returns to his employer the whole amount of the pure silver, as 

 well as the copper, without demanding any payment : he is amply remunerated by 

 that minute portion of gold. The new process of refining is a most beautiful che- 

 mical operation. The granulated metal is boiled in concentrated sulphuric acid, 

 which dissolves both the silver and the copper, leaving the gold nearly pure, in the 

 form of a black powder. The solution is then placed in a leaden vessel containing 

 metallic copper ; this is gradually dissolved, and the silver precipitated in a pure 

 metallic state. The sulphate of copper is also a valuable product, being employed 

 in the manufacture of green and blue pigments. 



Other immediate results of the economical production of sulphuric acid, are the 

 general employment of phosphorus matches, and of stearine candles that beauti- 

 ful substitute for tallow and wax. Twenty-five years ago, the present prices and 

 extensive applications of sulphuric and muriatic acids, of soda, phosphorus, &c., 

 would have been considered utterly impossible. Who is able to foresee what new 

 and unthought-of chemical productions, ministering to the service and comforts of 

 mankind, the next twenty-five years may produce ? 



After these remarks, you will perceive that it is no exaggeration to say, we may 

 fairly judge of the commercial prosperity of a country from the amount of sulphuric 

 acid it consumes. Reflecting upon the important influence which the price of sul- 

 phur exercises upon the cost of production of bleached and printed cotton stuffs, 

 soap, glass, &c., and remembering that Great Britain supplies America, Spain, 

 Portugal, and the East, with these, exchanging them for raw cotton, silk, wine, 

 raisins, indigo, &c., &c., we can understand why the English Government should 

 have resolved to resort to war with Naples, in order to abolish the sulphur mo- 

 nopoly, which the latter power attempted recently to establish. Nothing could be 

 more opposed to the true interests of Sicily than such a monopoly ; indeed, had it 

 been maintained a few years, it is highly probable that sulphur, the source of her 

 wealth, would have been rendered perfectly valueless to her. Science and industry 

 form a power to which it is dangerous to present impediments. It was not difficult 

 to perceive that the issue would be the entire cessation of the exportation of sul- 

 phur from Sicily. In the short period the sulphur monopoly lasted, fifteen patents 

 were taken out for methods to obtain back the sulphuric acid used in making soda. 

 Admitting that these fifteen experiments were not perfectly successful, there can be 

 no doubt it would ere long have been accomplished. But then, in gypsum (sulphate 

 of lime), and in heavy-spar (sulphate of barytes), we possess mountains of sulphu- 

 ric acid? in galena (sulphate of lead), and in Iron pyrites, we have no less abun- 

 dance of sulphur. The problem is, how to separate the sulphuric acid, or the sul- 

 phur, from these native stores. Hundreds of thousands of pounds weight of sulphu- 

 ric acid were prepared from iron pyrites, while the high price of sulphur consequent 



