132 
Basic Cinder as Manure. 
containing carbonic acid, and in dilute saline solutions, than is 
the ordinary mineral phosphate of lime ; and to this is doubtless 
due the greater efficiency of the basic cinder, provided it be 
very finely ground. The grinding was at first a great difficulty, 
principally owing to the fragments of steel present in the slag 
playing havoc with ordinary mills. This difficulty is, however, 
now overcome, and special machinery with roller mills is at 
work in several places for grinding the slag. 
From 1882 onwards a great number of field and pot-culture 
experiments have been carried on with the ground slag in 
Germany and other parts of the Continent, and the results, on 
the whole, have been very favourable to the use of the slag : so 
much so, that by far the largest proportion of the slag produced 
in England has been sold to go to the Continent. Some of the 
most carefully-conducted and most interesting of the culture 
experiments in pots have been conducted during several years 
by Dr. P. Wagner, Director of the Agricultural Experiment 
Station at Darmstadt, and certain of his experiments clearly 
show the importance of fine grinding. 
In this country, the first systematic field experiments were 
made in 1885, by Mr. Wrightson and Dr. Munro, on swedes. 
These experiments were made partly at Ferryhill, Durham, on a 
stiff, deep clay, deficient in lime, and partly at Downton, Wilts, 
on a light, chalky soil. The season was a bad one for roots, but 
in the stiff, clay soil, the basic cinder at the rate of 4 cwt. per 
acre gave excellent results — better than an equal weight of 
mineral superphosphate. On the chalk soil the results were not 
so favourable, but the cinder, especially if applied in rather 
large dressings, gave very marked good results. 
In 1880, the present writer, in conjunction with Mr. Russell 
Swanwick, carried out very numerous experiments with basic slag 
on the Royal Agricultural College Farm, both on swedes and 
on potatoes, and a few on grass land. Generally, the slag, which 
was used in varying amounts tip to 1 ton per acre, gave an 
increase of about 3^ tons of roots per acre over unmanured 
plots — not quite as much as was given by 3 cwt. of superphos- 
phate. The quantity of slag applied, whether 4 cwt. or up- 
wards, had little effect on the yield of the crop to which it was 
first applied : 4 cwt. and 0 cwt. gave as good results as 20 cwt. 
on the first crop. On potatoes, 10 cwt. of slag gave much the 
same results as 0 cwt. of mineral superphosphate. On grass, the 
slag had a good effect, but not quite equal to that produced by 
a somewhat smaller dressing of superphosphate. Other experi- 
ments were carried out in the same year by Mr. Warington, on 
Sir J. B. Lawes's farm at llothamsted ; by Mr. W. Field, junr., at 
