160 Miscellaneous Notices^ ^c. 



2. Amalgamation. 



The separation of the mercury from the silver, is here o. 

 clumsy, and comparatively, an expensive process. Instead 

 of using an iron retort, with two parts hke an alembic, placed 

 upon the common open French furnace ; the antique per 

 decensum method is the one resorted to. The amalgam is\ 

 placed under a large bell of copper which is encased for each 

 operation with unburnt bricks but so as to leave a space suffi- 

 ciently great for the quantity of charcoal requisite to produce 

 the heat required. The heat being a lateral one, the mer- 

 cury rises towards the top, collects in globules and falls 

 through a funnel and tube placed at the bottom of the bell 

 into a vessel of water beneath the whole ; or the whole bell 

 is filled with the vapor of mercury, which is condensed at the 

 lower part. Should you wish a drawing of the furnace, it 

 will give me pleasure to send you one. The furnace has a 

 fanciful appearance, like the tombs of the middle ages : the 

 bell being on the top and center of a quadrangle of mason- 

 ry ; at the corners of which are four pillars of the same, sup- 

 porting a pyramid, which serves as the dome of the furnace. 



3. Climate of Mexico. 



This country holds out great advantages to those persons 

 who suffer from those pulmonic affections, which arise from 

 too great action of the lungs on the arterial system, which I 

 think of consequence. Almost every degree of rarity of the 

 air can be obtained in this country, and certain degrees of it 

 can be obtained likewise, which are almost uniform for tem- 

 perature, from one season to another. In the city of Mex- 

 ico, breathing is attended with unpleasant sensations to ev- 

 ery stranger in ascending an elevation, be it great, or even 

 small. The action of the lungs is a labored one, and the 

 want of strength attendant upon their imperfect function or 

 performance, is very evident. I. found there, for the first 

 time in my life, a difficulty of breathing at night, frequently 

 waking with a sense of want of sufficient breath. At this 

 place nothing of the latter kind occurs, the elevation not be- 

 ing greater than about three thousand five hundred feet, but 

 still I cannot climb the hills and mountains here, as I was 

 wont to do in other countries, from deficiency of pulmonic ac- 

 tion. Since I have been here, a period of five months, the 

 greatest degree of heat in my room has been seventy-two 



