712 REPORT—1863. 
While being constantly renovated, a supply of oxygen is provided in a solid 
form by this hydrated oxide of iron. 
Venetian Red.—The manufacture of this article has long been carried on 
in this neighbourhood, and is noticed here, as it is so closely related to green 
copperas. It is made by calcining a mixture of copperas and some native 
hydrated oxide of iron, chalk, and gypsum. ‘The calcined mass is levigated 
and dried. About 4000 tons per annum are manufactured on the Tyne, and 
the price varies from £4 10s. to £5 per ton. 
Sulphate of Copper—This salt was formerly produced by roasting old 
copper in a reyerberatory furnace, and then dissolving the oxide in sulphuric 
acid, but it is now obtained in carrying out Longmaid’s process for decom- 
posing common salt by means of cupreous pyrites. The quantity made is 
about 100 tons per annum, which is all produced at the works of Messrs. 
J. and W. Allen. 
Resin Size.—This article is manufactured according to a patent obtained 
by Mr. W. 8. Losh, and is intended to produce a size suitable for paper- 
makers, and to supersede the old size in ordinary use, which consists of alum, 
resin, and soda-ash. Its manufacture has, however, been only partially 
developed, and not more than 100 tons yearly are produced; but a new and 
cheap size, which can be prepared ready for the use of the paper-trade, is, 
we think, a step in the right direction, and the theory of the sizing of paper 
is a field still open to chemists. 
Lamp-black.—The manufacture of lamp-black, we believe, is peculiar to 
this locality, and it is produced from bituminous coals. These coals are 
slowly burnt, at a dull heat, and with as small a supply of air as possible. 
The smoke is conducted into brick chambers, into which a jet of steam or 
water is passed, to assist in the better formation of the lamp-black. The 
quantity made is about 1200 tons annually. 
Grease.—This product is made to the extent of 2800 tons annually. It is 
chiefly produced from the distillation of resin, and in a locality ike New- 
castle, surrounded by extensive collieries and works, the consumption is con- 
siderable. Since the American war the price has been much affected, and, 
we are told, has advanced from £8 or £9 per ton to £22 per ton. 
Chemical Products of Gas-works.—The quantity of coal used in the manu- 
facture of gas on the three northern rivers, the Tyne, Wear, and Tees, amounts 
to about 100,000 tons. 
The products obtained are as follows :— 
875,000,000 cubic feet of gas ..........., £113,000 
5S, 000 tons ol COkb ae cee cin tth che siete wie 10,000 
23,800 gallons of crude naphtha ...... 2,800 
309,000 gallons of creosote oil ........ 1,250 
35D CO FORA AOL PUGEI 0 garg) atitveds ahaha sinshae 3,130 
600 tons of sulphate of ammonia... . 9,000 
£139,180 
The sulphate of ammonia is manufactured direct from the gas-water, in 
the following manner :—A large cylindrical boiler is filled two-thirds full 
with the gas liquor, and gently boiled. The gaseous products and steam are 
conducted into a mother liquor, from a previous operation, which is kept 
slightly acid. When no more ammonia comes over, a quantity of milk of 
lime is added to the boiler and a strong heat applied, until the colouring 
matters cease to be disengaged. The gaseous products are collected as before, 
