50 EIGHTH REPORT — 1838. 



muriatic acid. Caustic ammonia was added, and the precipitate 

 separated by filtration. Tlie precipitate was washed M'ith cold di- 

 stilled water, and in this state was exposed to the air for about six weeks 

 without the application of heat, when it appeai'ed quite dry. The 

 solution and washings from the precipitate were carefully evaporated 

 to dryness, but on digesting the same with water everything redissolved, 

 showing that all the silica had been precipitated by the ammonia. 

 The solution, after being gently heated, was mixed with oxalate of am- 

 monia, and the precipitated salt of lime thrown on a filter. The dry 

 precipitate obtained by ammonia was digested in the cold with con- 

 centrated muriatic acid, and the insoluble portion, after the ordinary 

 washing and ignition, Aveighed. The titanic acid was precipitated from 

 the filtered solution after being gently warmed by caustic ammonia, of 

 which reagent an excess was carefully avoided. The specific gravity 

 of the second specimen was 3'5128 ; hardness, G'75; — lustre, resinous; 

 — colour, cinnamon brown ; — cross fracture, granular and uneven; — 

 opaque, but translucent in thin plates. Before the blowpipe alone on 

 charcoal, it became white, but did not fuse. With carbonate of soda 

 in the oxidizing flame it fused into an orange bead. Its locality is not 

 known. The following is the composition of the two specimens : — 



Silica 31-05 29-35 



Titanic Acid 43-90 4-2-60 



Lime 24-80 24-90 



Water I'OO 1-15 



100-75 98-00 



and the formula, 



3 (Ca O, 2 Ti Oj + 2 (Ca O, 2 Si O3). 



On a Neto Process for the Extraction of Silver from Lead. 

 Sy H. L. Pattinson, 



The object of this communication was to lay before the Association 

 an account of a discovery made by the author some time ago, the ap- 

 plication of which to practice constitutes a new process in the arts, and 

 forms an important improvement in the extraction of silver from lead. 



Adopting the estimate of Mr. J. Taylor, in 1 828*, that the quantity 

 of lead raised annually in England and Wales amounts to 45,5C0 tons, 

 the author states that it all contains silver, in variable proportions, but 

 with so much of constancy in the proportion of silver in the lead ore of 

 each vein, that it is easy to arrive at a tolerably accurate knowledge of 

 the quantity of silver contained in the lead of each district. 



Of 22,000 tons of lead yielded in the district of Alston Moor, it is 

 believed that 16,000 tons contain silver at the rate of from 6 to 12 oz. 

 per ton, and 6000 from 3| to 6 oz. per ton — the average being about 5. 



* See Records of Mining for tliat year ; also Reports of the British Association, 

 vol. v., for an estimate, by Mr. J. Taylor, of the quantity of lead raised in Great Bri- 

 tain iu 1835. 



