XXVII. O/z the Preparation of CalomeL r 



j^j i>y Mr. Joseph Jewel. 



'In our last number, page 93, we mentioned that Messrs. 

 Howard and Co. had introduced an important improvement 

 in the preparation of this essential article of the pharmaco- 

 poeia. It is the discovery of Mr. Joseph Jewel, one of the 

 partners, who gives the following specification of his in- 

 vention, for which he has taken out a patent : __„ - 



'^ Calomel, or mercurlus dulcis, as usually prepared, is 

 at first a hard crystalline substance, and requires to be 

 pounded and triturated with water, either in a mortar or on 

 a slab with a muller, or in a mill. After having been 

 ground or triturated for a considerable time, more water 

 is added, and the whole well stirred up. The finer particles, 

 which remain suspended for a short time, being poured off 

 with the water into another vessel, and left to subside, the 

 water is then decanted, and the fine powder dried for use. 

 The coarser particles arc again submitted to the operation of 

 grinding and washing ovcr^, until the whole be finished. 

 Now the nature of my invention is to produce the effect of 

 the grinding or trituration above described, in a more per- 

 fect manner, during the last sublimation of the calomel ; 

 which I do as follows : ■ '' *^ ''■"^'*' o 



*' I take calomel, or mercurius dulcis, broken into small 

 pieces, and put into an earthen crucible of the form of a 

 long barrel, so as to fill about one half thereof. I place the 

 crucible on its side in a furnace provided with an opening, 

 through which the mouth "of the crucible projects about an 

 inch. I then join to the mouth of the crucible an earthen- 

 ware receiver, having an opening at its side to receive ihe 

 open end of the crucible. This receiver is about half" filled 

 with water. I lute the joint with a mixture of sand and 

 pipe-clay. The receiver has a cover, v/hich cover has a side 

 continui'd upwards for containing water, with a chimncv or 

 tube in it, to allow the escape of steam from the water be- 

 low. I then apply a fire around the crucible, sumcient to 

 rai^e the calomel in vapour, and force it through the mouih 

 .of the .crucible into the receiver; v. here, by the water,* 

 ^^ J 3 while 



