OF ARTS AND SCIENCES : OCTOBER 13, 1868. 61 



time, that a part of the lead salt might be changed to sulphovinate of 

 lead and pass into solution. This idea was sufficiently improbable in 

 view of the known facts that dilute alcohol and weak sulphuric acid are 

 unfit for making sulphovinic acid, and that but little if any of the acid 

 can be formed, even from tolerably concentrated liquids, unless the mix- 

 ture of alcohol and sulphuric acid be heated artificially. The idea was 

 nevertheless put to the test of experiment, as follows : — 



100 c. c. of alcohol of 59 per cent, 5. c. c. of oil of vitriol, and a 

 quantity of recently precipitated sulphate of lead, were placed in a 

 stoppered bottle, and the mixture was frequently shaken during an 

 interval of three months. The clear liquid was then decanted, diluted 

 with water, and saturated with sulphuretted hydrogen gas. Not the 

 slightest coloration indicative of lead was produced. 



100 c. c. of similar alcohol, mixed with sulphuric acid, sulphovinic 

 acid, and sulphate of lead, gave no reaction for lead when tested after 

 the lapse of three months. 



2d. Though the idea seemed highly improbable, it was still possible 

 that the sugar in the wine might in some way exert a solvent action 

 upon sulphate of lead. It was found, however, when 100 c. c. of alco- 

 hol of 59 per cent, and 5 c. c. of oil of vitriol, together with a quantity 

 of sugar and of precipitated sulphate of lead, were left to themselves 

 for three months, that the clear supernatant liquid held no trace of 

 lead in solution. For that matter, it was found that a mixture of sul- 

 phuric acid and much sugar-water was capable of precipitating all the 

 lead even from an aqueous solution of acetate of lead. The filtrate 

 from the sulphate of lead thus pi'ecipitated gave absolutely no indica- 

 tion of lead when tested with sulphuretted hydrogen, not even when a 

 considerable quantity of the liquid was evaporated to dryness, inciner- 

 ated, treated with nitric acid, and again evaporated before applying the 

 reagent. 



3d. The most probable hypothesis of all, however, was, that a cer- 

 tain proportion of lead could be held dissolved in presence of sulphuric 

 acid, even in an alcoholic solution like wine, by the action of various 

 soluble alkaline salts capable of decomposing and of being decomposed 

 by sulphate of lead ; for it is a well-known fact that very considera- 

 ble quantities of sulphate of lead can be held dissolved in water by 

 means of many acetates, citrates, and tartrates, and by various other 

 salts. 



To test this idea, the following set of experiments has been carried 



