WITH THE MARINE ACID. 3 rf f 



mercury is capable to extinguifli, and others de- 

 line accurately the weight of mercury to be em- 

 ployed. Were the form and quantity of corro- 

 iive mercury always the fame, and equal pains 

 bellowed, it would be of little confcqucnce 

 which of the methods was preferred; but as this 

 is by no means the cafe, more circumfpecliou 

 becomes abfolutely necelTary. Lcmery, indeed, 

 in other refpecls moil attentive to determine 

 weights and proportions, contends that corro- 

 fivc cannot enter into combination with more 

 crude mercury than three-fourths of its weight. 

 The authors of the London and Edinburgh Phar- 

 macopoeias deliver the fame opinion. I mull own, 

 however, that for the reafons already adduced, 

 I confulcr it much fafer to employ crude mercu- 

 ry in excefs than in too final! proportion; efpc- 

 cially as the fuperabundant mercury may be 

 favcd with very little additional trouble. If 

 \vhite mercurial precipitate is taken, a (mall, and 

 fomctimer- no addition of crude mercury is requir- 

 ed. According to Lemery, fublimation alone 

 \vill be fullicient ; and Neumann had fo little 

 doubt that white mercurial precipitate ilood in 

 no need of crude mercury, that he pronounces it 

 to be already perfectly fimilar to mercunus dul- 

 cis. This opinion is not without fomc appear- 

 ance of truth, cfpecially as J. F. Carthcufer * 

 has obferved, that white mercurial precipitate, 



not 



* F.lem. Chcm. 



