NITBATES FROM ATMOSPHERE SCOTT. 383 



take such work, and no doubt, as time goes on, it will become more 

 and more difficult to get men for this work. Of course, these very 

 thin seams can only be worked when the coal is of very good quality 

 and prices are good. We may take it, therefore, that Sir William 

 Ramsay's suggestion has plenty of scope in the seams of under 15 

 inches thick, of which there are many. 



There are also many pits which contain the particular coal known 

 as "• cannel," which is specially suitable for making gas. A case in 

 point is the Leen Valley coal field of Nottinghamshire, where the 

 heam known as " tophard '' will be worked out in 20 years. Now, the 

 top part of this seam consists of inferior cannel coal, and since the 

 gas companies took to producing low illuminating gas and enriching 

 it with other materials than cannel, practically none of it has been 

 raised to the surface. 



In the five collieries of the Leen Valley, namely Hucknall, Lenby, 

 Annesley, Bestwood, and Newstead, there are millions of tons of 

 cannel coal, to say nothing of slack left from the seam of tophard 

 coal and a great deal of timber. 



The shafts are already down and roads made, and supposing that 

 lower seams prove unremunerative, then all this cannel coal could be 

 burnt out for a supply of gas. There are certainly 15,000 acres of 

 such coal within 120 miles of London. 



EQUALIZING THE LOAD. 



The problem of utilizing the electric energy of power stations at 

 periods when such stations are working on low loads is beginning 

 to attract the attention it deserves. The ideal for any power house is 

 to secure a load of 100 per cent load factor, and there is no doubt 

 that if greater efforts were made in this direction the price of power 

 would come down considerably. 



The valleys have been filled in, to some extent, by po\Ner and trac- 

 tion loads, but as these also have to be supplied at the same time as 

 lighting the result was not as beneficial as it was thought it would be. 



Now an electrochemical or metallurgical proposition is quite dif- 

 ferent, because such plants can often be shut down during the 24 

 hours for an hour or two: the load can therefore be adjusted to just 

 fill up the valleys. 



The Yorkshire Electric Power Co. was early in the field with this 

 method of working, in connection with the carbide of calcium plant 

 at Thornhill. It is of interest to note, by the way, that this power 

 company is supplying electric energy to 15 collieries. 



At Legnano a nitric acid plant of 4,000 kilowatts has been at work 

 for some time past, which operates only during the night and certain 

 hours of the day, when power is supplied at a cheap rate from the 

 hydroelectric station by the Societa Lombarda per Distribuzione dell' 

 Energia Elettrica. Current is supplied bj' the power company at 

 50,000 volts, and, although the price charged does not. transpire, it is 



