60 PROCEEDINGS OF THE SCIENTIFIC ASSOCIATION. 
join chemically with the juice. A fine white article is 
produced, but one that is stated by the English manufac- 
turers to be almost useless on account of the action of .the 
spirit. The last and the best method that I have experi- 
mented with is to drive off the water by means of steam at 
100° C (boiling over a naked fire cannot b9 made use of, as 
a large quantity of the juice becomes burnt and de- 
stroyed). This drying is accomplished in large leaden 
trays fitted in boxes, a space of an inch and a half being 
allowed between the lead and the box. Steam from a 
boiler under ordinary atmospheric pressure is allowed to 
pass into the box and circulate around the leaden tray ; the 
gum is then poured into the tray and kept constantly 
stirred up by wooden stirrers so as to prevent a film 
forming at the surface. In the course of an hour and a 
half the mass will have become almost dry ; it is then 
removed from the leaden tray and exposed to the air for 
two or three days to become entirely dried and hard. 
This process furnishes us with an article having a pink 
colour and which requires but little purification to ren- 
der it fit for exportation. Great care must be taken in all 
these processes that no vessel or article of Iron or Tin 
be employed in the preparation, as by its action the colour 
of the substance is changed and becomes almost black, 
owing to the presence of tannin or tannic acid in the 
juice itself. To obviate this, all vessels or tools employed 
are made either of lead or copper. 
The Gutta Perelia prepared by any of the above 
processes will find a ready market in England, France, 
Germany and the United States, and of course an article of 
superior quality will bring a higher price. Any samples 
prepared as above may be purified by simply boiling with 
