Proceedings of the British Association. 441 



inly given. It appears, from the use of guano in the production of 

 he prussiate of potash, that the quantities of this element are always 

 inderstated. 



A conversation ensued as to the relative value of the Peruvian and 

 African Guano. It was remarked, that in some cases it had been found, 

 hat the weight of the ear produced by the use of guano, was too great 

 jr the stalk to support ; consequently it fell, and the grain was injured; 

 nd information as to a means of giving greater stiffness to the straw, 

 /as much to be desired. — Mr. Hunt stated, that it had been found in 

 ae west of Cornwall, that the use of the China stone, a decomposed gra- 

 ite, the felspar of which contained much silicate of potash, produced a 

 traw of a very remarkable degree of stiffness. — Mr. Warrington sugg- 

 ested that silicate of soda might be very readily formed at all places 

 ear the sea, by calcining together sea-sand and common salt. This led 

 ) a conversation on the power which plants possessed of substituting 

 3da for potash in different districts. — Prof. Liebig said, he had been 

 agaged in the analysis of plants growing in different districts extend- 

 lg from Giessen to the sea. It was found that corn, peas, beans, and 

 rass, contained a larger portion of soda as they grew nearer and nearer 

 ae sea coast : thus satisfactorily proving, that plants could substitute 

 Dda for potash, without injury to their growth. No plants were found 

 1 which there was not potash, but there were many in which there was 

 o soda. It had been asked in what proportions soda and potash were 

 )und in the animal economy? Soda existed largely in the bile and 

 lood — potash was found most abundantly in the muscles, hence the 

 sason was evident why the use of soda (common salt) with the 

 >od of man, was universal. It was quite evident that plants could sub- 

 ;itute one constituent for another — it had been even found, that in the 

 )bacco plant lime had been replaced by potash. — In answer to other in- 

 uiries, Prof. Liebig remarked, that the alkalies in plants were not in 

 jmbination as organic constituents; they could be dissolved out. Car- 

 on, on the contrary, formed a part of their structure. Carbonic acid 

 as absorbed by plants, and served, uniting with hydrogen and with 

 ater, to form a series of compounds containing varying proportions of 

 lese elements. An organized body is formed by the action of chemical 

 •rces ; its structure shows it is not the result of physical force. We 

 ave the formation first of the vegetable acids of sugar, &c. ; oxalic 

 iid, tartaric acid, and citric acid were vehicles of transfer, combining 

 i they did with the potash or soda of the plants, from which were at 

 ngth separated the carbon which went to the composition of the vege- 

 ible structure. 



