TRANSACTIONS OF THE SECTIONS. 51 
this respect than aluminium; a bar of this metal, suspended by a string and struck 
with a Beccr, emits a musical sound like that of glass. He finds that the same 
occurs with compact homogeneous wood-charcoal. The best piece experimented 
on was 11 inches long, 3 inch wide, and weighed exactly 82°05 grammes, When 
struck, it gave the high treble C; and a piece weighing 2°05 grammes being 
struck off it, it gave the C sharp exactly. The note of the scale produced in these 
circumstances depends on the square of the length and the diameter of the substance 
struck; the duration of the sound, upon the duration of vibration produced by the 
shock. Ccteris paribus, glass will ring after a blow 4 to 5 seconds, aluminium 
3 to 4 seconds, and charcoal 13 to 2 seconds, according to his experiments. The 
densities of these three substances are somewhat similar :— 
Hel caret belie ianln ad cipcrs th Abr 2:49 
LM ibe ashe mei iRud cove cintooIbome 2-62 
Amorphous carbon ..........+- 2-50 
It appears that some years ago a performer at Astley’s Theatre executed a piece 
of music upon fragments of charcoal of different dimensions, suspended on strings. 
On the Constant Increase of Organic Matter in Cultwated Soils. 
By Dr. T. L, Purpson. 
On January 6th, 1863, an article appeared in ‘The Times,’ entitled “ Exhaustion 
of Vegetable Mould,” followed by a “leading article” upon the same subject, in 
which the writers stated that the organic matter of soils under cultivation is 
being constantly exhausted, that the vegetable mould is a most valuable constituent 
of soils, and that its loss is not replaced in any way in our present systems of agri- 
culture. The author refutes these extraordinary statements by bringing forward 
the determination by analysis of the proportion of organic matter in soils sub- 
mitted to culture for many years, compared with the quantity present in unculti- 
vated soils; and, supported likewise by the opinions of the late Professor Johnston 
and Baron Liebig, he proves that the organic matter of soils constantly increases 
by cultivation, whilst their fertility steadily decreases,—this fact being due to the con- 
stant loss of potash, lime, phosphoric acid, &c. 
The vegetable mould or humus supplies chiefly carbonic acid; but as plants get 
abundance of this in the air and water they absorb, that given by decomposition of 
humus constitutes in most cases an excess. A certain amount of organic matter 
in a soil generally betters the physical condition by rendering it more porous, &c. 
The author insists also on the necessity, in analyses of soils, of determining the 
amount of moisture by heating the soil to 105° C, as long as it loses weight, before 
proceeding to determine the amount of organic matter present, 
Researches on the Manufacture of Prussiate of Potash, By the late Joun Lux 
and Tuomas Ricuarpson, M.A., Ph.D., F.RS.L., MRLA., Fe, 
The celebrated manufacturing experiment of Messrs. Bramwell and Hughes to 
obtain cyanogen from the nitrogen of the air and charcoal, induced the authors to 
examine the old process of producing prussiate of potash, in order to ascertain what 
became of the nitrogen of the animal matter. 
The experiments were all made with the same mixture of materials, which was 
formed of pure horn finely rasped, potash, and clean iron filings. A small quantity 
of water was added to assist in sake an intimate mixture, which was afterwards 
carefully dried, and then ground to a fine powder. This mixture was composed of 
orn... Sa AO eee .. 16:00 
Potash os such ©. « bushsteieeeeree aes 17°72 
ETON, geass «ea Sy stats bre fee 300 
Moisture, 6 4..35,.6. ome Pes nates 3:28 
40:00 
A potash-charcoal was made by soaking 13 ozs. of wood-charcoal with a solution 
of 4 ozs. of potash, and then fully dried. fe 
