THE DISEASE AFFECTING THE ELM TREES. 
345 
potash, the first in the form of superphosphate, the second in the form of 
wood ashes. It is clear that in forestry one cannot use manures freely, 
since the result would not repay the expense ; but bearing in mind that 
superphosphate is very cheap manure, and that wood ashes can be obtained 
at slight cost, it would seem reasonable to employ these fertilisers. With 
them the luxurious vegetation due to the excess of nitrogen can be re- 
pressed, the nutrition regulated, and the tissues formed in a regular and 
perfect way. 
As the Elm groves of which I speak are used solely for the growth of 
timber, and the use of leaves and branches for feeding cattle is a second- 
ary consideration, it is necessary to keep them thinned out with great 
care, since trees which are much damaged by pruning off the side 
branches cannot make good building wood. 
Understand, then, that you must not strip the trunks, leaving only a 
little leafy top ; all the branches which the tree throws out must be 
preserved, and room must be allowed for the natural habit of the tree to 
form itself into a leafy and extended pyramid. The greater the number 
of leaves, the greater the absorption of aerial carbon, and Consequently 
the greater the nutrition. This carbon, with the elements of water (oxygen 
and hydrogen), constitutes, after various chemical changes, the first 
compound, forming a cellular and ligneous part — in a word, the wood. 
When the first flowers appear, the best plan is to pick off as man}^ 
of them as possible, thus causing the phosphorus which would have been 
used up in the formation of the fruit to remain in the tree, and contribute 
in forming new wood cells and tissues. Besides, the flowers which remain 
on the tree will produce ample seed of superior germinating power. It is 
a good thing to open up the plantations, particularly those parts where the 
trees, being close together, have difficult access to air and light. 
When timber recently cut shows deep cracks, it is difiicult to do any- 
thing with it ; but if the cracks are small, one can at least prevent an 
increase of the evil. 
For this purpose the hewn wood should be put in a tank or pool, for 
ten to twelve days, filled with water containing the following solution per 
hectolitre : Acetate of copper, 10 grains ; chloride of sodium, 20 grains ; 
and chloride of calcium, 10 grains. If there is not sufficient depth of 
water to cover the timber, dissolve the same quantity of salts in a decalitre 
of water, and with this frequently bathe the outside of the trunk. It is 
as well also to submit wood that does not show any cracks to the same 
bath in order to prevent cracks developing later on. For chloride 
of calcium it is necessary to employ pure lime 19, clo-hydric acid 
32, water 49 parts, chloride of calcium crystallised 100. It may be pre- 
pared by putting into a tub the acid and water, adding broken-up 
calcareous stone until it no longer effervesces and the liquid loses its 
acidity. Then it is filtered through a cloth. In the less humid soils I 
believe the Walnut tree would give good results ; in the other lands one 
might try the Hazel-nut, Chesnut, and some varieties of White Mulberry, 
natives of cold climes. Also one might try the Lote tree on dry positions 
protected from the cold. 
