the Trcfencc of Lead in Wine, 347 



„ The reagent in queftion was made in the proportions and 

 manner indicated by the perfon who had employed this teft*: 

 equal parts of fulphur and potafh (cauilic) were diflblved in a 

 fufficient quantity of diftilled water; fome drops of this folu- 

 tion, which the faid perfon called fulphuret, and to which 

 he ought to have given the name of hydrogenated fulphuret, 

 were mixed with the fufpe&ed wine, and no other change 

 was produced, but that which ought to take place in pure 

 wine of the fame kind, viz. a decompofition of the fulphuret, 

 either by the malic acid or by the tartareous acid of the 

 acidulous tartrite of potafli. Had this wine held in folutiou 

 a particle of lead, the latter muft neceflarily have immediately 

 formed, not a fait, as the author of the note fays, but a me- 

 tallic fulphuret, infoluble, and eafy to be diltinguifhed by its 

 colour; being at firft of a reddifli brown, and paffing foon to 

 dark brown. But as tjie wine did not experience from this 

 reagent any other change than that arifing from the faid de- 

 compofition, giving firft a white cloud, then fome traces, 

 fcarcely fennble, of a depofit of the fame colour, which is 

 nothing elfe than the fulphur precipitated, it is Hill proved 

 the wine did not contain a particle of lead. 



6th, Another part of the fame kind of wine, but known to 

 contain lead, was employed to confirm the proof (5) by a 

 counter-teft : a drop of the folution of acetite of lead was 

 put into it, and hydrogenated fulphuret being then added, 

 I immediately obtained the infoluble fulphuret of lead of the 

 colour which I have mentioned. 



7 th, Having at hand all the apparatus neceffary for thefe 

 refearches, I applied them to red wine fold in a tavern. One 

 part of this wine being mixeo 1 with a few drops of the folution, 

 of acetite of lead, and then with hydrogenated fulphuret, the 

 fulphuret of lead was immediately announced bv a change of 

 colour. The purple pafTed to blackifh, and foon after the 

 metal was detected by an abundant depofit of the fame colour. 

 One part of the fame red wine being mixed with hydrogen- 

 ated fulphuret, without adding acetite of lead, the difference 

 of the phenomena was fo (inking, that it alone is iufheient 

 to give confidence to perfons whofe regard for their health 

 may induce them to make trials of this nature : the change 

 of colour is no lefs fpeedy in pure wine than in that which 

 contains lead, but this change is altogether oppofite to that 

 which I have here noted, lied wine «ontaining lead grows 

 darker by hydrogenated fulphuret : pure red wine, on the 

 other hand, when the reagent is mixed with it, exchanges its 



This indication, under the title of a note on rite experiment, was 

 tranfmitttd to me with the wine. — O. R. 



purple 



