340 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



PROPER SEASON FOR FELLING TREES. 



It is said that if trees felled in summer are immediately 

 stripped of their bark, the timber'thus obtained will be in no 

 way inferior to that from trees which are cut down in winter. 



PREPARATION OF PEAT. 



Mr. Alloway has lately delivered a lecture upon peat, be- 

 fore the Society of Arts of London, in which he points out the 

 difficulties that have hitherto prevented the utilization of 

 this substance as a fuel. He adverts to the expensive ap- 

 paratus used by various persons for treating it, and especial- 

 ly for condensing the peat by pressure, and states that it is 

 impossible to do this satisfactorily by the ordinary means, 

 owing to the peculiar spongy structure of j)eat and the diffi- 

 culty of drying it. His method consists in first breaking up 

 the freshly-cut clods with a mallet, by which they are disin- 

 tegrated, after which they are to be placed in a ditch in the 

 peat-bog filled with water, where they are to remain, forming 

 a thick mush, until the time comes for further treatment. 

 Early in April the operation of making into bricks is com- 

 menced, and a small quantity is taken up at a time and 

 moulded rapidly by hand into pats, which are then laid upon 

 slats and allowed to drain and dry, this being generally ac- 

 complished in the course of a few days. 3 B, September 14, 

 525. 



1IUMATE OF AMMONIA. 



It has already been observed that plants grown on soil rich 

 in silica and poor in humus contain less silica in their ash 

 than those grown on soil poor in silica but rich in humus. 

 Since an excess of silica is always present in soil, the amount 

 taken up by a plant must clearly depend on other circum- 

 stances than the quantity at its disposal. Thenard has re- 

 cently thrown light on the subject by showing that humic 

 acid forms, with ammonia and silica, very permanent acid 

 compounds. These compounds are soluble in very dilute 

 alkali, from which solution they can be separated unchanged. 

 They lose nitrogen -only at a high temperature. Humic acid 

 does not combine with silica unless ammonia be present. It 

 appears probable from these considerations that humic acid 



