TRANSACTIONS OF SECTION M. 741 
Pot and laboratory experiments show that when plant residues are added to 
soil or sand, a vigorous decomposition of the cellulose by aérobic organisms ensues 
and appreciable quantities of nitrogen are assimilated from the atmosphere. 
How far this has a bearing on the practice of green manuring and the introduc- 
tion of any organic residues to the soil, is a question for closer investigation. 
4. Agricultural Value of Carbonate of Lime recovered from Causticising 
Plant. By Professor James Henpricr, B.Sc., F.I.C. 
Great quantities of precipitated carbonate of lime are obtained as a by- 
product from causticising plant. In many parts of the country, at any rate, this 
precipitated chalk is thrown on the dump-heap as a waste product, while it may 
be that the surrounding fields are hungering for carbonate of lime. 
This waste product as obtained from the dump-heap contains about 50 per cent. 
of moisture, and is a somewhat tenacious putty-like substance. The dry matter 
is, as might be expected, mainly carbonate of lime. Small quantities of other 
substances are present, which vary considerably, according to the nature of the 
recovery process used. A little silicate of lime is always present, and there is 
generally some organic matter. The material is always alkaline, and sometimes 
strongly so. The soluble matter and the alkalinity were determined in a number 
of samples. The alkalinity is in some cases due to calcium hydrate, and in others 
to sodium hydrate and sodium carbonate. It varies greatly in different samples. 
In certain samples an alkalinity due to soda, and corresponding to as much as 
6 per cent. of sodium hydrate, was found. In other samples the alkalinity was 
under 1 per cent. expressed as sodium hydrate. 
The soils of the north-east of Scotland are almost without exception poor in 
lime, yet this substance goes to waste, and even when offered for nothing to 
farmers in the wet state little use has been made of it. One reason for this is that 
in the wet state it is difficult to spread. It is, however, easily dried, when it 
forms a fine powder, which is easily distributed. 
A number of field experiments have been carried out with this carbonate of 
lime, in which it has been compared with other forms of lime, such as burnt lime 
and ground limestone. The experiments have all been made on land deficient in 
lime and very subject to finger and toe in turnips. So far as they have gone 
they show that whether the results are measured by increase of crop or by diminu- 
tion of finger and toe disease, the precipitated carbonate of lime does at least as 
well as any other form of lime. It has, on the whole, acted better than an equal 
quantity of commercial ground limestone. This might be expected, as it is very 
much finer, and is therefore more thoroughly mixed with the soil. It was found 
that the presence of a small percentage of sodium hydrate and sodium carbonate 
had no prejudicial effect on its action. 
5. The Drainage of Soils practically free from Carbonate of Lime. 
By Professor James Henprick, B.Sc., F.1.C. 
6. The Rate of Liberation of Hydrocyanic Acid from Linseed. 
By’S. H. Corns, Mise acc, 
A farmer considers linseed to be one of the safest cattle-foods, but the 
chemist has shown that linseed readily liberates hydrocyanic acid. The author 
has attempted to measure the rate of liberation of hydrocyanic acid from linseed 
under conditions somewhat similar to those occurring during digestion. The 
rate at which hydrocyanic acid is liberated from linseed depends upon many 
details, but among the many causes which retard the liberation of hydrocyanic 
acid, the degree of acidity is pre-eminent. So sensitive is the enzyme responsible 
