130 CONSTRUCTION AND MANAGEMENT OF SMALL GASWORKS. 



been suggested. It is quite possible that by this means it 

 would be possible to utilize the liquor in works too small to 

 warrant the erection of a plant. Considerable business is 

 done in the way of collecting liquor from neighbouring 

 small works. At Salisbury, for instance, we have for years 

 taken the total make of three neighbouring small works. 

 The apparatus must necessarily be of the cheapest and 

 simplest form available, as there is not much margin for 

 interest on the outlay, but a toy apparatus is not of much 

 use as a commercial venture. If the plant is not equal to 

 a minimum of about 5 cwts. of sulphate per twelve hours, 

 the profits are eaten up by wages and incidental expenses, 

 and what is saved in interest on outlay is lost in other ways. 

 If practicable, it is better for a few neighbouring works to 

 combine, so as to secure an aggregate of 30,000 gallons a 

 year or so; but it may pay to put down a plant for dealing 

 with even as little as 4,000 gallons. 



One frequently hears the yield* of ammonia spoken of as 

 a fixed quantity, but, as a matter of fact, it varies widely 

 with different classes of coal, and according to the methods 

 of carbonization. Somerset and Welsh coals give a much 

 lower yield than Derbyshire or Staffordshire. In larger 

 works, a yield of one ton of sulphate per TOO tons of coal 

 is obtained, but I never heard of that proportion being 

 reached in a small works. 17 Ibs. weight of pure ammonia 

 requires 49 Ibs. of pure sulphuric acid to neutralize it, and 

 the result is 66 Ibs. of sulphate. Commercial oil of vitriol 

 runs 70 to 80 per cent, pure, and can be tested by the 

 hydrometer. An acid that is sold as 80 per cent, pure 

 should make something more than its own weight of 

 sulphate. Pure sulphate of ammonia contains about 25! 

 per cent, ammonia and 74 J per cent, acid, and the com- 

 mercial salt as produced at a gasworks will be 98 or 99 per 



