46 British Association for the Advancement of Science. 



dissolving 1 grain of nitrate of silver in 500 of water , and apply- 

 ing this solution like the browning liquid. The number of repe- 

 titions of the nitrate of silver water would depend on the shade 

 of brown required, but Mr. Ettrick found from 1 to 5 or 6 amply 

 sufficient. The barrel is to be placed in the sunshine to obtain a 

 dark color. The last process was to apply the scratch brush freely, 

 though lightly, and then polish the whole by bees' wax. Mr. Et- 

 trick had, since the date of his own invention, discovered the pro- 

 cess used by workmen generally, and long kept secret, but by the 

 plan described a much finer brown is attainable than that gained 

 by the trade. 



Fossil Fishes — Agassiz's great work going on. — Mr. Dawson 

 exhibited a collection of fossils from New South Wales. — Mr. 

 Murchison communicated some information which he had lately 

 received from M. Agassiz, who was bringing out some new livrai- 

 sons of his great work on fossil fishes, and he mentioned that in 

 order to enable that gentleman to carry on his Avork, a further 

 grant of money would be recommended by the Geological Com- 

 mittee. The remains of fish had been found to be the most valu- 

 able of all indexes for determining the ages of rocks, as there was 

 a plain separation of these animals in formations of different ages. 

 Mr. Murchison showed drawings of some of these fossils, and re- 

 marked that in the lias and the older beds the fishes were charac- 

 terized by a tail quite different from that belonging to those found 

 in the newer formations, and he exhibited on a board representa- 

 tions of some of the peculiarities of those discovered in the Silu- 

 rian rocks. He must record the names of Drs. IJoyd and Lewis 

 as having given him material assistance in the collection of these 

 remains. He had found remains like the shagreen or tubercula- 

 ted skin of some recent fishes, also extraordinary teeth belonging 

 to a species termed Stogodus Priscodontus, and fish called Sera- 

 phim, by the quarrymen, from their seeming to possess only head 

 and wings, to which the name Pterigodus has been given ; also 

 many others which M. Agassiz would soon have described and 

 published. 



Heat in Mi?ies. — Mr. R. W. Fox stated, that at the Bristol 

 Meeting of the Association he had been requested to make ex- 

 periments on the Electricity of Mineral Veins. He had been un- 

 able to do much since that time — he had merely to mention, that 

 he had made experiments at Middleton Teesdale, in the county of 



