ON ARTIFICIAL REFRIGERATION. 939 



"It will be easily seen tliat the whole arrives tlnougli the whole leDgth 

 of M by the perforated tube j' m,jm. The corabiuation will thus be 

 effected under the best conditions, which arc still more favoured by the 

 current of cooling water, whicli, entering at j c, first runs over the sur- 

 fiice of M through the worm m a, m a, before entering the tubes of the 

 absorber J, and here the i^rodnction of the solution which was to be 

 formed is finished. 



"As will be easily understood, it is necessary to cairy it out of the 

 absorber, and cause it to give back the trimethylamine, which should 

 again produce the freezing action, and thus render it permanent. 



"To obtain this latter result it must be reconducted to the vaporizing 

 (Condenser. For this purpose the tube m c, m e, m c, m e, passes from the 

 absorbing vessel M to the said vaporizing condenser. By following the 

 course of the tube m c, m e, m e, m e, it will be seen that instead of going- 

 direct to the vaporizer B, it is at first drawn in by the pumi) ^ST, which is 

 necessary, since there is only a very low pressure in the absorber J, and 

 a higher jiressure in the vaporizer B, and that moreover it is caused to 

 pass through the series of plates of the changer K; and I will now de- 

 scribe this apparatus. 



"It has been seen that very hot liquid was sent out of the vaporizing 

 condenser B, and that, on the contrary-, very cold liquid was discharged 

 from M, and which should be returned into the vai^orizer B. It is then 

 requisite to exchange the temx)eratnres, that is to say, to impart the heat 

 to the liquid which is to enter the vaporizer B, and the cold to the liquid 

 which is to enter the absorber J, and it is for this purpose that the 

 exchanger K is employed. It consists simply' of three plates of sheet iron 

 united together at their peripheries by one or two rows of rivots. This 

 arrangement is shewn in Figure 2, on a preceding ])age. 



"The plate a m is the exchange plate. 



"In the space II, E, circulates the liquid to be reheated, which may 

 escape through the tube r m; in the space S, S, on the other hand, comes 

 the liquid whicli is to impart the heat. 



"As will be easily seen by referring to K, the tAvo liquids run in oppo- 

 site directions, and consequently exchange their heat. The liquid which 

 enters the rectifier C by the tube a b, a &, is as hot as possible ; and that 

 which leaves by the tube 1c h, I: h, and enters the absorber J after having 

 run through the worm L, is as cold as possible. 



"It remains to describe some of the parts which are necessary to in- 

 sure the working of the apjjaratus. These consist of six pumi)s i)laced 

 round the steam engine A, viz: 



"1. An air pump, shewn at O. 



"2. Another similar air pump x>hiced behind the pump O, and on a 

 level with it, and is consequently not seen in the Drawing, but which I 

 will call pump No. 2. 



"3. A chloride of calcium pump P. 



