VOL. LVII.] PHILOSOPHICAL TRANSACTIONS. 485 



which cannot be condensed; and in several operations these fumes are very hurtful 

 to the lungs. By the following method of distillation these fumes are totally 

 condensed, which makes a great saving in some distillations, and the operator is 

 in no danger of being hurt by any pernicious vapours. This new method con- 

 sists in making the fumes pass by a small glass tube through water, which thus 

 becomes charged with the vapours, that would otherwise escape. 



Description of the apparatus, pi. 14. — In fig, 1, a is a retort; b a receiver, 

 with a spout at bottom, for the distilling liquor fo run into the bottle c; the 

 recipient has also a small opening on one side at d ; e a crooked tube -Jg- and -^ 

 of an inch bore; f a vessel containing water. 



'. The crooked tube e is fitted to the spout d of the receiver by means of a cork 

 with a hole in its middle, and then well covered with lute; the other end of it 

 goes to the bottom of the vessel f, to the mouth of which it is fitted by a cork, 

 with a semicircular notch in it as at g, but without any lute to fasten it, as 

 there must be a small vent for the escape of the elastic air, and this is the only 

 vent in all the apparatus for that purpose. By this apparatus the fumes are 

 obliged to pass through the water in f, and there deposit all they contain, except 

 their elastic air. ii 



In most distillations there is a quantity of air absorbed at different times dur- 

 ing the process; and in this case the external air would press on the water at f, 

 and force it by the tube into the vessel c, which might spoil the distilled liquor. 

 This may be prevented by letting air into the receiver or bottle c, by boring a 

 hole through the lute; this however may be inconvenient, on account of the 

 constant attendance which is necessary; but the following apparatus will prevent 

 it. See fig. 2. It consists in fitting an empty vessel h, to the apparatus de- 

 scribed before in fig. 1. By this means the water is forced into h, and by the " 

 stopper at l it may be emptied, and put back into the vessel f; the crooked 

 tubes D and i are fitted to h, by a cork with two opposite semicircular notches, 

 as at K, and then well covered with lute. 



Exper. 1. — On the distillation of sal ammoniac with quick-lime. — 12 lb.* of 

 British sal ammoniac, and 26 lb. of quick-lime were powdered, mixed, and put 

 into the iron body a, fig. 3, and when the apparatus -j- was luted, a gallon of 

 water was poured on it through the orifice b, which was immediately stopped; 

 the lime growing hot produced a vast quantity of elastic air, which though highly 

 charged with volatile alkali was condensed by the water in f, fig. 2, the air only 

 escaping at the top of this vessel with hardly any sensible volatile alkaline smell. 



* In all the experiments avoirdupois weight was made use of. — Orig. 



+ The spout of the stone head belonging to the body a, fig. 3, is to be luted to the receiver b, 

 fig- 2.— Orig. 



