25S 



Account of a Cast-Iron Boiler 



[Apri% 



35 years; unless it be affirmed that the discoveries of Scheele 

 and of Klaproth, and the general chemical law developed by 

 Richter, contributed nothing to the improvement of the science. 

 Such national reproaches as those which Mr. Chenevix casts upon 

 the Germans may gratify spleen, and furnish food for malignity ; 

 they may display a happy turn for sarcasm and repartee ; but 

 they are not only unjust, but in every respect beneath the dignity 

 of a philosopher, and even inconsistent with common candour 

 and honesty. 



Article II. 



Account of a Cast-Iron Boiler for evaporating saline Lej/s. 

 By Mr. William Ramsay. 



(To Dr. Thomson.) 



SIR, Glasgow, Jan. 16, 1813. 



It is a fact well known to those who are interested in chemical 

 works, that boilers of cast-iron cannot be employed with safety 

 either in lixiviating ponderous substances, or in concentrating 

 the solution of any salt which crystallizes at the surface of the 

 liquid by evaporation ; because in the former case the mass of 

 the materials resting on the bottom of the vessel ; and in the 

 latter^ the crystallized salt falling down, is apt to fix on the 

 bottom of the boiler, and ultimately to rend it. 



Although boilers made of malleable iron are not subject to the 

 same inconvenience from these causes, yet in a number of cases 

 they cannot be employed with safety : in the solution of a salt, 

 for instance, which contains the smallest predominance of any 

 of the mineral acids, these acting on the joints and rivets, in a 

 short time corrode, and render them unserviceable, which fre- 

 quently causes not only loss but disappointment. 



From these causes I have lost several cast-iron boilers, when 

 the workman did not pay proper attention to the agitating of the 

 salt which was dissolving, or in not removing that which had 

 fallen down by the concentrating of the liquid. 



To avoid this expense and inconvenience, I have adopted a 

 method for building up cast-iron boilers^ v;hich is particularly 

 calculated for insuring their safety in evaporating any dense 

 liquid ; and having now had the experience of its safety for more 

 than two years, I can with greater propriety recommend it to 

 those placed in similar circumstances. 



The boilers which 1 have found most advantageous to use for 

 tlie evaporation of dense liquids, where the salt crystallizes at 

 the surface by evaporation (such as muriate of soda or sulphate 

 of potash)^ are those commonly called sugar-pans, which con- 



