178 CHEMICAL MANUFACTURES ON THE TYNE. 



the elegant process of the late Mr. H. L. Pattinson, which consists in 

 submitting calcined magnesian limestone to the action of carbonic acid 

 and water, under pressure. The magnesia dissolves out as bicarbonate 

 of magnesia, from which the neutral carbonate of magnesia is preci- 

 pitated by the application of heat. The quantity manufactured is said 

 to be about 250 tons per annum. 



Superphosphate of Lime. — The manufacture of this article was 

 commenced at Blaydon, in 1844, by Dr. Richardson, soon after the pub- 

 lication of Liebig's celebrated report on agricultural chemistry. Various 

 materials are employed as the source of phosphate of lime — viz., bones, 

 bone ashes from South America, exhausted animal charcoal from the 

 sugar refineries, coprolites from Suffolk and Cambridgeshire, phosphate 

 from Spam, Sombrero guano, &c. Improvements have been introduced 

 in the manner of mixing the acid with these substances in drying 

 and in the riddling of the superphosphate. The quantity produced 

 amounts to between 15,000 and 16,000 tons per annum. 



Pearl Hardener. — This article has only recently been manufactured 

 here, and its introduction is due to Dr. Jullion, who has applied it to 

 the hardening of paper. It is produced by precipitating hydrated sul- 

 phate of lime from a perfectly pure solution of chloride of calcium, by 

 means of sulphuric acid. Great care is taken in its preparation, and it 

 is being generally introduced among the manufacturers of paper. The 

 quantity made is said to be about 2,000 tons per annum. 



Sulphate of" Iron. — The first manufactory for the production of 

 green copperas in England was founded about the year 1579, when one 

 Matthew Falconer, a Brabanter, " did try and draw very good brimstone 

 and copperas out of certain stones gathered in great plenty on the shore 

 near unto Minster, in the Isle of Sheppey." Mr. Thomas Delaval 

 commenced to manufacture copperas at Hartley about the year 1748, but 

 he subsequently sold the manufactory to his brother, Lord Delaval, and 

 by an Act of Parliament, 11th of George III., 1771, power was given 

 to Sir Francis Blake Delaval to grant to Sir John Hussey Delaval, in fee 

 simple, all the copperas works then and there existing, which may 

 enable us to form some idea of the importance then attached to this 

 manufacture. The late Mr. Barnes and Alderman Forster erected the 

 first copperas works on the Tyne, at Walker, in 1798, which are still in 

 operation. The quantity at present manufactured is about 2,000 tons 

 per annum, and the process is still the same, but Mr. Thomas Barnes has 

 applied the refuse crystals to a novel purpose. This refuse was, and is, 

 generally thrown away, but Mr. Barnes uses it as a manure on his farm, 

 on the thin soil which lies on the magnesian limestone. He finds 

 that the depth of the soil is gradually increasing by the disintegration 

 of the rock, and that the more he uses, the more satisfactory are the 

 results. The beneficial effect of the copperas is doubtless partly due to 

 the natural decomposition of the carbonate of lime with the sulphate of 

 iron, and partly to the action of the peroxide of iron on the organic 



