and Attached Water. 



23 



boration or explicit adoption by foreigners of the views I 

 ventured to advance has given me perhaps more satisfaction 

 than if they had been only accepted by English physicists, I 

 may be allowed to express some regret that the latter do not 

 yet appear to be awake to the interest and importance of the 

 subject. It gives me, therefore, unusual pleasure to offer them 

 this my eighth memoir on this branch of Molecuiar Physics. 



In this memoir I shall first make a study of the ammonia 

 group in its behaviour with water. I add a little to our 

 knowledge of ammonia itself in this respect Then are 

 examined the effects of replacing one or more of the hydrogen 

 equivalents by ethyl. Then will be described in some detail 

 the behaviour with water of some aniline salts. 



Secondly (§§249-255), I shall shift the region of my 

 inquiry upwards on the thermometric scale, and include in it 

 temperatures at which the solid fuses per se, and shall thus 

 establish the continuity of the phenomena of fusion with those 

 of solution, making clear the fact that certain bodies, originally 

 solid, may at high temperatures become miscible with water 

 in all proportions. It will be shown how this latter branch of 

 the inquiry, apart from its purely physical interest, has a great 

 geological one, as it throws light on the pyrohydration of 

 igneous formations, just as the cryohydration in floes has 

 thrown light on the formation of those masses. 



§ 233. Ammonia. — Anhydrous ammonia, NH 3 , according 

 to Faraday becomes solid under a pressure of 20 atmospheres 

 at a temperature of — 75° C. According to Fourcroy and 

 Vauquelin, a perfectly saturated solution (? saturated at air- 

 temperature) freezes between —38° and — 41° C, forming 

 shining flexible needles; at — 49° 0. it freezes to a grey 

 gelatinous mass. 



Starting with a 33'3-per-cent. solution, I made solutions of 

 various strengths, and found that pure ice separated from 

 them at the following temperatures : — 



Table XLV. 

 Showing Separation of Ice from Solution of Ammonia. 



Per cent, of 

 NH 3 . 



Per cent, of 

 water. 



Temperature 

 of beginning 

 solidification. 



Body 

 separated. 



1 



99 



o 

 - 0-8 



Ice. 



3 



97 



- 32 





5 



95 



- 5-0 





10 



90 



-128 





15 



85 



-21-4 





20 



80 



-434 



» 



