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XIX. Intelligence and Miscellaneous Articles* 



THE INVENTION OF THE WATER AIR-PUMP. BY II . SPRENGEL. 



[Statement** 



ALETTEE addressed to me by Dr. Sprengel under date of No- 

 vember 1st, 1872, in which he says, " Perhaps it will not have 

 escaped your observation, that the invention of the water air-pump, 

 which you have constructed after the principle of my mercury air- 

 pump, according to your paper published in 1868 on the Washing 

 of Precipitates, is almost everywhere attributed to you," induces 

 me to make the following statement. 



The interesting discovery, that by means of columns of liquids flow- 

 ing downwards a more perfect vacuum can be produced than was pos- 

 sible by the air-pumps hitherto in use, belongs solely and only to 

 Dr. Sprengel. He in his researches on the Vacuum (Journal of 

 the Chemical Society, January 1865), brings prominently forwards 

 that water is, from a practical point of view, the only liquid which 

 could come into consideration as a substitute for mercury, used in 

 the instrument described by him, and that it is not unlikely that 

 such an instrument, adapted for water, might possess advantages 

 which air-pumps of other constructions have not, particularly in 

 hilly countries, where the large volume of a natural waterfall might 

 be rendered available. In the theoretical considerations on the 

 action of his instrument, which immediately follow the above, it is 

 noticed that it is simply the reverse of the trompe, with this addi- 

 tion, that the supply of air is limited, while that in the trompe is 

 unlimited. 



If in the face of these facts, which are open to all, any one attri- 

 butes to me, as I must conclude from Dr. Sprengel's letter, a share 

 in his discovery, I can regret this only all the more keenly, as in 

 my treatise on the new method of filtration I could not possibly 

 have expressed myself with regard to Dr. Sprengel's claims more 

 loyally and precisely than I have done. There I have stated ex- 

 pressly that I have constructed the pump, used for nitrations and 

 described by me in detail, after the principle of Sprengel's mercury 

 air-pump. It was the only apparatus of the kind which Dr. Sprengel 

 described, consequently the one to which alone I could refer. 



Heidelberg, November 5, 1872. (Signed) E. Btjnsen.] 



Expressing my best thanks to Professor Bunsen for the above 

 statement, I beg to add that since 1860 I have been using for labo- 

 ratory purposes a water-trompe, as described by me in Poggendorff's 

 Annalen for 1861 (vol. cxii.), which (by reversing the action) led 

 me in 1863 to the new method of air-rarefaction. Water was the 

 first liquid which I used in my first pump, constructed during the 



* Translated from Ann. Chem. Pharm. vol. clxv. p. 159, by H. Sprengel, 

 authorized by Professor Bunsen. 



