348 JVotice 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 

 from C to H, and 36 from I to K. IH is a 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 is a 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 S =38 

 centimetres. The recipient differs little from the retort ; it is fig. 7, 

 the mouth of which should enter the aperture of the retort. The 

 recipients are in stone ware and support the fire well. Fig. 8 is 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 employed ; the fire is 

 kept up for twenty four hours. The charge for each:retort is 2 lbs. 

 or 128 lbs. for a gallery, giving from 70 to 79 lbs. of smoking sul- 

 phuric acid. This result is not constant ; frequently much less is 

 obtained. To obtain a like product the wood should be dry and the 

 fire well conducted, otherwise on inspection, some of the retorts will 

 be found to contain a weak acid and in less quantity. Those of the 

 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 pro- 

 ducts. The twenty four hours having expired, the fire is suffered to 

 fall ; when sufficiently cool, the lute that attaches the recipient to the 



