12S New Acid found in Alkaline Prussiates. 



teriovly. And further, (as is already the practice in some 

 engines, and therefore not exclusively claimed by me,) 

 I cause the water raised by the engine to pass otf through 

 another ascendin^;" tube than the one attached to the steam 

 vessel, but connected with it at some part lower than the 

 oil or other substance employed in it is ever suffered to de- 

 scend to in the working of the engine. The improvement 

 which I have just mentioned, of introducing oil into the 

 pipe attached lo the steam vessel of such engines, may also 

 be introduced without applying heat externally to the steam 

 vessel ; but in this case part of the effect which would other- 

 wise be !j;ained is lust." 



XXVr. Extract of a Letter from M. RlxcK, ofTreysa, 

 on a new Acid found in Alkaline Prussiates *. 



J- ou are undoubtedly acquainted with the Prolusions of 

 Winter!, and you will have veritied the most part of his 

 arguments. I should wish to know how you have judged 

 t)f this work. In Germany, this' author and his book were 

 at first exceedingly ill used. They rejected indiscriminately, 

 and without examination, all that M. Wintcrl had advanced. 

 But of late hi:-- opinions have been discussed, and people 

 begin to do him justice. His system has now many sup- 

 porters, and deserves, by all accounts, considerable atten- 

 tion. 



Among the observations of Winterl, wcfind the follow- 

 ing: that in the prussiate and carbonate of potash there 

 exists a salt which dissolves in alcohol, does not precipitate 

 the solution of iron in a blue but in a red colour, and is 

 essentially distinguished from prussiate of potash by its other 

 properties. Although the Prussian lixivium has been care- 

 fully examined by many chemists, none of them has recog- 

 nised this salt. However, it is found in it; and I myself 

 have obtained it. 1 am occupied at this moment in a train 

 of experiments on this subject, as well as on the formation 

 of prussic acid, which have already afforded some interest- 

 ing results, and which promise to furnish me with some 

 new facts. 



Some carbonpaed iron which 1 examined offered me some 

 particular phrenomena. Weak acids exercise hardly any 

 action, when cold, upon this iron. They require for this 

 effect the aid of heat, or to be concentrated. The nitric 



• From J'an J!\Io7:s's Journal, vol. vi. 



acid 



