24 Frederick Guthrie on Salt- Solutions 



Judging by the analogy, which will appear more clear in 

 the sequel, it seems that the body mentioned by Fourcroy is 

 a subcryohydrate, and that the gelatinous mass mentioned 

 still contained too little water for the cryohydrate. I find 

 that a 33'3-ner-cent. solution does not crystallize at — 80° C; 

 and I have as yet been unable to obtain the true cryohydrate. 



§ 234. Ethyl- Ammonias. — The ammonias whose relation- 

 ship to water have next to be described were obtained from 

 Kahlbaum of Berlin. They were verified by means of their 

 boiling-points, their platinum double chlorides, and by titration 

 with standard hydrochloric acid. Those which I here employ 

 were found to be pure. 



§ 235. Ethylamine. Boils at 18° C. — The solutions of this 

 base were made by dropping an indefinite quantity into 

 a narrow-necked weighed bottle, putting in the stopper, 

 weighing, surrounding by a freezing-mixture, and running 

 in the proper quantity of distilled water from a burette. 

 When the quantity of wafer was small, it was dropped in 

 from a capillary tube until the proper weight was reached. 



The first five solutions, namely those containing 0*99, 5, 

 10, 15, and 20 per cent, of ethyl-ammonia (NH 2 C 2 H 5 ) , showed, 

 on cooling, the separation of the easily recognizable ice- 

 crystals. On further cooling the 20-per-cent. solution, the 

 separating crystals became opaque, betraying the cryohy- 

 drate ; this occurred at — 13°* 9, whereupon the temperature 

 became stationary. After ten or twelve grams had solidified 

 at — 13° # 9, the remaining liquid was poured into a fresh tube 

 and reduced to the same temperature. The same operation 

 having been performed three times, the liquid was considered 

 pure ; 3*589 grams of it were weighed in a stoppered bottle, 

 diluted with water, over-neutralized with hydrochloric acid, 

 evaporated in a water-bath in a platinum dish until the 

 chloride became quite hard on cooling, heated to incipient 

 volatilization, and weighed. There was thus obtained 1*3415 

 gram chloride of ethyl-ammonium or 0*7407 ethylamine, which 

 corresponds to 20*64 per cent. 



On cooling a stronger solution than this, solidification 

 begins at a higher temperature, reaches a maximum between 

 30 and 35 per cent., and again falls, passing out of the range 

 even of a solid carbonic-acid cryogen. As there is only one 

 tenth of a degree difference between the points of initial 

 solidification of the 30- and 35-per-cent. solutions, and guided 

 by the general shape of the curve, I made a 32*4-per-cent. 

 solution, and found that solidification began at — 8° C. 



It is well known that anhydrous ethylamine is not solidifiable 

 in a solid carbonic-acid cryogen. Accordingly, the solid which 



