158 Scientific Intelligence. 



able to prepare the new salt in larger quantity. By draining off 

 the mother liquor while still hot, and washing the solid part of 

 the contents of the tubes with water, a green product consisting 

 of crystalline fragments was obtained, about 0*25 gram being 

 yielded for each tube. On analysis, the salt afforded 26-98 per 

 cent of S0 4 and 54*49 of Cu ; giving the formula of a tricupric 

 sulphate CuS0 4 (CuO) 2 (H„0) 2 or Cu 3 SO f (H,0) 2 , which requires 

 53-75 per cent Cu and 27-07 S0 4 . The salt is permanent when 

 heated in the air to 190°, is insoluble in water, soluble in dilute 

 sulphuric acid. The crystalline form was determined by Miers 

 to be orthorhombic. — J. Ghem. Soc, xlvii, 375, June, 1885. 



G. F. B. 



9. On the Molecular Weight of liquid Water. — Thomsex has 

 called attention to the fact that the conclusion reached by Raoult 

 in his researches on the freezing point of saline solutions, that 

 water possesses, in the condition of liquid, twice the molecular 

 weight which it has in the condition of vapor, coincides with the 

 conclusion to which he himself had come from his investigations 

 on the constitution of hydrated salts. In his thermochemical 

 researches, Thomsen says : A glance at the table of heat of hy- 

 dration of hydrated salts shows that the water molecules enter 

 often in pairs with the same heat-change ; a fact explicable either 

 by supposing that the molecules of water are symmetrically 

 placed in the molecule of the salt, or, and perhaps more probably, 

 that the molecular weight of liquid water is twice that of water 

 vapor. The similarity of these conclusions, from widely different 

 fields of investigation, is noteworthy. — Ber. Berl. Ghem. Ges., 

 xviii, 1088, April, 1885. G. f. b. 



II. Geology and Minekalogy. 



1. The volcanic nature of a Pacific island not an argument for 

 little or no subsidence. — In the remarks on this point in § 13 (p. 

 100) of my paper on the Origin of coral reefs and islands, I refer 

 to the great depths found in the ocean by soundings in the vicin- 

 ity of Hawaii, and speak of the facts as favoring the idea of more 

 subsidence about that southeastern end of the group than along 

 the northwestern, although the latter is the coral island end. 

 Another example of similar character, but more striking, is af- 

 forded by the region of the Ladi*ones. This north-and-south 

 range of islands has its largest volcanic islands in the southern 

 part, and dwindles in the opposite direction to islands which are 

 little more than tufa cones ; and 200 miles south of Guam, the 

 largest island, the Challenger found a depth of 4,475 fathoms 

 (26,850 feet), one of the deepest regions of the ocean. It hence 

 may be that Guam, like Hawaii, is a large island, not because of 

 small subsidence, but because of continued eruptions that made it 

 large in spite of the sinking that was in progress. The ques- 

 tion arises how far the depths in these particular cases are due to 

 the undermining effects of volcanic eruption. There are coral 



