230 J, Evans on Geological Changes in the 
tion was cold, readily dissolved in an excess of the reagent, and 
the more readily the larger the quantity of free hydrochloric 
acid present. If the solution was heated to boiling during the 
precipitation, the precipitate was not easily redissolved; but by 
digesting it for several hours with a very large excess of oxalic 
acid complete solution was finally effected. In a similar solu- 
tion of the chlorid, a strong solution of sulphate of potash pro- 
duced a precipitate, which in the presence of free hydrochloric 
acid readily dissolved in an excess of the reagent if the solution 
was kept cold. But if the solution was heated during the pre- 
cipitation, the precipitate did not thus redissolve; but it imme- 
diately disappeared on adding a small amount of dilute sulphu- 
ric acid. From a solution of the chlorid of zirconium, ammonia 
throws down a gelatinous precipitate, but this precipitation was 
hy 
found in many text-books. The two modifications of zirconia, 
distinguished by Berzelius, seem to be repeated in many of its 
compounds, and malacone stands in the same relation to ordinary 
zircon that the soluble oxalate and sulphate do to the insoluble 
varieties. The malacone at Rockport is unquestionably in pro- 
cess of alteration, but whether the original mineral was the or- 
dinary zircon or what we may call the normal malacone, I have 
not yet been able to determine. 
Art. XXVIL.—On a possible Geological Cause of Changes in the 
boce of the Awis of the Earth’s Crust; by Joun Evans, 
_ AT a time when the causes which have led to climatal changes 
In various parts of the globe are the subject of so much discus: 
sion, but little apology is needed for calling the attention of this 
Society to what possibly may have been one of these causes 
though it has apparently hitherto escaped observation. 
That great changes of climate have taken place, at all events 
in the northern hemisphere of the globe, is one of the best 
* Proceedings of the Royal Society, xv, p. 46. 
* 
