89 



in diameter, and, though the fire was so small, the sand could be 

 easily made red hot in that nearest to the fire, sulphmic acid dis- 

 tilled freely, and, in calcining magnesia, the bottom of the retort was 

 melted. Mr. Kiernan altered according to our views a furnace 

 which heated a steamboiler of the capacity of 50 gallons, its area 

 had been 1 5 inches,it did not raise the steam in less than two hours, 

 and was a nuisance to the vicinity. The fire-place of the fumivore 

 was 10 by 16, much too large as we discovered, and it made the 

 water boil violently in 25 minutes. We endeavoured to ascertain 

 what the effect was more accurately, a fumivore had been adapted 

 to a still in the laboratory of the Apothecaries-Hall, with a fire-place 

 of 9 by 16, we charged the still with 125 gallons of water and kin- 

 dled the fire, having weighed a quantity of coal for the experiment; 

 in an hour and five minutes the water began to distill, and the pro- 

 cess was continued for 5 hours more, in which time 67 pounds of 

 jcoal were burned and 70 gallons of water (s) distilled, which gives 

 8. 87 pounds of water vaporised by every pound of coal, something 

 above Watts's maximum, although the form of the still was not 

 the most advantageous, its bottom being concave so that the flame 

 did not touch the central part of it. We have tried many other ex- 

 periments with equal success, but it would be useless to detail them 

 as they are similar in their results to those already stated, and we 

 have not yet had an opportunity of making any on a very large scale. 

 It is (t) however necessary to observe that the performance of these 



VOL. XIII. o 



(i) During the first hour 45 pounds of coal were introduced into the furnace, so that it was 

 full when the distillation commenced, and 1 reckon that 67 were consumed afterward, as that 

 quantity was supplied, and the fire-place was full when the experiment was ended. 



{f)\i a large quantity of coals be introduced at once, the furnace ceases to consume its 

 smoke, on account of the reduction of the temperature, but tliis continues only for a few se» 



