‘= 
348 Notice of the Smoking Sulphuric Acid. 
ash pit, being 35 by 20 centimetres. FF are the recipients, in posi- _ 
tion; they are adapted to the retorts, the position of which is seen 
in Fig. 3. GG are two chambers, constructed for efflorescing the 
sulphate of iron; thus giving an acid containing less water than oth- _ 
erwise would be obtained, provided the copperas was calcined in its. % 
natural state: they extend the entire length of the furnace and par- 
allel with the fire hole: they are 40 centimetres from K to C, 34 _ pe 
from C to H, and 36 from I toK. 1H isa plate of iron, supporting. 
the recipients. ‘The bars that support the combustible are in brick, 
having a thickness of 3 centimetres. The extreme height of the front 
elevation is 150 centimetres. The whole length of the gallery is 4 
metres. 
Fig. 2 is a horizontal cut, following CD. Fig. 3 is a perpendicu- 
lar cut, showing’ the position of the retorts. Fig. 4 is the plan. Fig. 
5 isa side elevation, having no other conductor for the smoke than is 
seen in O, passing off through the side and superior ventilators of the 
building. Fig. 6 is the retort, represented on double the scale} from 
P to P =10 centimetres, 8 at the mouth, (S,) and from P to $=38 
centimetres. The recipient differs little from the retort; it is fg. 7> 
the mouth of which should enter the aperture of the retort. The 
recipients are in stone ware and support the fire well. Fig. 8s the 
charging spoon, having a length of 45 centimetres; it has a groove 
running nearly the length of the instrument, represented in the cut. 
Fig. 9 is the scraper used for cleansing the retort of the colcothar. 
_ The retorts remain in their horizontal position until they are bro- 
ken, or until the necessity of making other repairs requires their re 
moval. They are charged with the white-sulphate of iron, by the 
means of the spoon represented. ‘The recipient is then adapted and 
the whole luted, with a mixture of saw dust and clay. In this state 
the gallery is heated; wood is the combustible 0] loyet ; the fire.6 
kept up for twenty four hours. The charge for each retort is 2 Ibs. 
or 128 lbs. for a gallery, giving from 70 to 79 Ibs. of smoking sul- 
phuric acid. This result is not constant; frequently much less 1 
obtained, To obtain a like product the wood should be dry and the 
fire well conducted, otherwise on inspection, some of the retorts W 
be found to contain a weak acid and in less quantity. Those of. 96 
recipients which contain a weak acid are known by their not smo” 
king ; it is distributed in this state, by piece-meal, into the other a 
ucts. The twenty four hours having expired, the fire is suffer - ro 
fall; when sufficiently cool, the lute that attaches the recipient t0 
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