WITH THE MARINE ACID. 



viclcnt, that tilings of a different nature have been 

 exprdfed under the fame name ; an error by 

 no means unattended with danger. For it may- 

 happen, that inftead of the white mercurial pre- 

 cipitate which a phyfician fhall have ordered 

 for his patient, mercurial calx, mercurial fait, 

 or a mixture of both may be adminftcrcd. Thcfe 

 fubftartcds, though they agre* in form and ex- 

 ternal appearance, yet in their properties and ef- 

 ficacy they arc in no way fimilar. For, if we 

 add the muriatic acid or common fait to a ni- 

 rrom folution of mercury, we iliall obtain a ge- 

 nuine mercurial fait; but, if we take the volatile 

 alkali, a mercurial calx will be precipitated, from 

 Which all the acid can be walhcd away by wa- 

 ter. Some writers have diflinguiflicd tlr.j calx 

 by particular names. Teichmeyer calls u, 'vr- 

 pethum album*, and in the firft editions of the 

 London pharmacopoeia it is defcribed under the 

 appellation of mercurius pre dp itatus dulcis. It is 

 altogether milder than the white precipitate, 

 and lefs volatile. Doflie contends, that white 

 mercurial precipitate fliould be prepared by 

 mixing fixed alkali with a folution of corrofive 

 mercury. There is no doubt, that in this way 

 a white matter is often precipitated; but Doflie 

 did not know that it never happened unlefs old 

 alkali, and fuch as had abforbcd the aerial acid, 

 was employed. 



Za As 



'* Inftit. Chym. 



