52 Perkins' 1 Steam Engine. 



half the fuel commonly used, for a given power, the weight 

 not to exceed one third of ordinary condensing engines, and 

 not to occupy more than one-third the space ; with absolute 

 security from the dangerous effects of explosion. 



3. On the explosion of Steam Boilers ; by Jacob Per- 

 kins, Esq. 



It has been generally considered a well established fact, 

 that the caloric of steam, at a given elasticity, is invariably 

 the same, when in contact with water ; but this is far from 

 being the case. It may be and often is, so generated as to 

 indicate very high degrees of temperature without a corres- 

 ponding increase of power ; so as evidently to prove, that 

 temperature alone, cannot be relied on as a measure of the 

 elastic power of steam. Many experimentalists have thus 

 undoubtedly been led into error, especially in reference to 

 high temperatures. If any part of the boiler which contains 

 the steam be suffered to become of a higher temperature 

 than the water contained in it, from want of a sufficient sup- 

 ply, the steam will readily receive an excess of caloric, and 

 become surcharged with it, without acquiring proportional 

 elasticity. In some recent experiments, I have heated steam 

 to a temperature, that would have given all the power that 

 the highest steam is capable of exerting, which would have 

 been 56,000 pounds to the square inch, if it had had its full 

 quantum of water ; yet the indicator showed a pressure of 

 less than five atmospheres. Having satisfied myself, by re- 

 peated experiments, as to the certainty of this curious fact, 

 the thought struck me, that if heated water were suddenly 

 injected into the superheated steam, the effect would instant- 

 ly be, the formation of highly elastic steam ; the strength of 

 which would depend upon the temperature, and quantity of 

 the surcharged steam, and of the water injected. To ascer- 

 tain the truth of this theory, I made the following experi- 

 ments. 



A generator was filled with water, and heated to about 

 500 degrees, and consequently, exerted a force of about 50 

 atmospheres ; but the pressure valve being loaded to about 

 60 atmospheres, it prevented the water from expanding into 

 steam. The receiver, which was destitute of both water and 

 steam was heated to about 1200 degrees; a small quantity 

 of water was injected into the generator, by the forcing 



