572 General Notices, 



To obtain approximative results as to the quantity of sulphur in the water- 

 cress seeds and the plants which they yielded, the following experiments were 

 made. The seed (100 grains ?) was heated to redness in ; a retort, and the 

 gases disengaged were received into a solution of potash; acetate of lead was 

 added to the alkaline liquor as long as precipitation occurred. The precipi- 

 tate was of a brownish colour, and consisted of hydrate, carbonate, and sul- 

 phuret of lead ; the two former were dissolved by dilute nitric acid, and the 

 sulphuretof lead remained, which, after washing and drying, weighed - 95gr. 

 which indicated 0'129 gr. of sulphur. According to this experiment, 100 gr. 

 of the seed contained 0*129 gr. of sulphur. 



The young plants obtained from the growth of 100 grains of the seed were 

 similarly treated. Their weight was 2040 gr. ; they yielded, by the above- 

 described process, 15" I gr. of sulphuret of lead, equivalent to 2*03 gr. of sul- 

 phur : consequently the dried plants contained more than fifteen times as 

 much sulphur as the 100 gr. of seed which produced them. 



According to this, 100 lb. of the dried plants would yield nearly -i. of 

 an ounce of sulphur, although grown where none could be obtained by the 

 roots. 



As the growth of the young plants of water-cresses took place in a soil 

 devoid of sulphur and sulphates, and in a room which contained no sulphur- 

 ous vapours, the origin of the sulphur, M.Vogel remarks, is to him a perfect 

 enigma, and at present he confesses that he is unable to give a satisfactory 

 explanation of it. (Joum. de Pharm. et tie Chim., Mar. 18. 1842, as quoted 

 in Phil. Mag. for July.) 



Soils. — In affording warmth to plants, the earth is of considerable utility, 

 and the power of accumulating and retaining it varies as much in soils, as the 

 proportions of their constituents. Sir Humphry Davy found that a rich 

 black mould, containing one fourth of vegetable matter, had its temperature 

 increased in an hour from 65° to 88° by exposure to the sunshine, while a 

 chalk soil was heated only to 69° degrees under similar circumstances ; but 

 the first, when removed into the shade, cooled in half an hour 15°, whereas 

 the latter lost only 4°. This explains why the crops on light-coloured 

 tenacious soils are in general so much more backward in spring, but are 

 retained longer in verdure during autumn, than those on black light soils; 

 the latter attain a genial warmth more readily, but part with it with equal 

 speed. The following experiment, which has often been successfully repeated 

 upon light as well as tenacious soils, demonstrates how greatly the colour of 

 a soil influences the accumulation of heat. Coal-ashes were sprinkled over 

 half the surface of beds sown with peas, beans, &c, and on these the plants 

 invariably appeared above ground two or three days earlier, obviously on 

 account of the increased warmth ; it being a well-known fact that dark bodies 

 absorb caloric more readily, and in larger proportions, than those of lighter 

 hue. (Cambridge Chron. and Joum., May 28. 1842.) 



Trenching stiff" Soils. — By the old method of ridging or trenching, we do 

 not obtain such a thorough pulverisation of the soil as may be desirable. 

 During my twelve years' service at Cannon Hall, where I had to contend 

 with a stubborn and clayey soil, I found the method which the annexed 

 diagram may serve to explain answer my wishes better than any other that [ 

 could hit upon. Let a, b, c,d represent a section of the ground to be 

 trenched 2 ft. deep. In 

 the first place, the ground 

 is measured out in longi- 

 tudinal beds, 4 ft. wide ; 

 this done, the top spit of 

 the bed e is laid on the 

 bed g; and the second Fig. 56. Section of Ground for trenching. 



spit of the bed e is laid 

 on h. The first or top spit of the bed / is then laid on the bed i, and the 



A 





sx 



■•. 





I 



' e ,' 



J 



! i 



"1 





A 



