Intelligence and Miscellaneous Articles. 155 



early as 1696 ; but a hundred years later " the art of improving wine 

 by litharge was taught in England as a method perfectly free from 

 danger " *. 



The sulphuric acid in the sample of wine examined by me was pro- 

 bably added with the view of removing the dissolved lead resulting 

 from the previous use of litharge. It is not unlikely that the addi- 

 tion of the free acid was preceded by that of a solution of sulphate 

 of ammonium. 



In seeking for an explanation of the fact that a certain proportion 

 of lead may remain dissolved in wine, even in presence of free sul- 

 phuric acid, the following hypotheses suggest themselves : — 



1st. It seemed not impossible, in case a mixture of weak alcohol, 

 dilute sulphuric acid, and sulphate of lead was left to itself for along 

 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 mixture of alcohol and sulphuric acid be heated artificially. 

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



100 cubic centims. of alcohol of 59 per cent., 5 cubic centims. 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 cubic centims. 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. 



2nd. Though the idea seemed highly improbable, it was still pos- 

 sible that the sugar in the wine might in some w r ay exert a solvent 

 action upon sulphate of lead. It was found, however, when 100 

 cubic centims. of alcohol of 59 per cent., and 5 cubic centims. of oil 

 of vitriol, together with a quantity of sugar and of precipitated sul- 

 phate of lead, were left to themselves for three months, that the clear 

 supernatant liquid held no trace of lead in solution. For that mat- 

 ter, it was found that a mixture of sulphuric acid and much sugar- 

 water was capable of precipitating ail the lead even from an aqueous 

 solution of acetate of lead. The nitrate from the sulphate of lead 

 thus precipitated gave absolutely no indication of lead when tested 

 with sulphuretted hydrogen, not even when a considerable quantity 

 of the liquid was evaporated to dryness, incinerated, treated with 

 nitric acid, and again evaporated before applying the reagent. 



3rd. The most probable hypothesis of all, however, was, that a 



* William Graham's ' Art of Making Wines from Fruit, Flowers, and 

 Herbs.' London, sixth edition. 



