48 REPORT — 1841. 



act less beneficially at subsequent periods of their application than they did at the 

 first, admits of being explained on the recognised principle, " that stimuli lose their 

 full effect upon living matter when frequently repeated." 



Dr. Daubeny adduced several facts, which led to the inference, that nitrates of 

 soda and of potass operate favourably upon certain crops by communicating to them 

 nitrogen, and that the reason why these salts sometimes have appeared to leave the 

 land in a worse condition than it was in before their use, is not that they are stimuli, 

 and therefore amenable to the law above quoted, but is because the free supply of 

 nitrogen afforded by tli^ir decomposition had caused the plant to absorb a larger 

 portion of those other ingredients, such as phosphate of lime, silicate of potass, 

 &c., which are present only in a limited quantity in the soil, thus tending to exhaust 

 the latter of these materials, and causing thereby an inferior crop to be produced in 

 the following year. 



Now though it may be true that the nitrates in this manner indirectly stimulate 

 the vital energies of a'plant, yet it was conceived that the term stimulus had better 

 be abandoned with reference to such cases, as its adoption might lead to an erroneous 

 impression in the mind of the farmer, with respect to the proper mode of restoring to 

 the land its original fertility. 



If the theory suggested by the author be the true one, it will follow, that the pro- 

 per remedy would be, not to discontinue the use of the nitrates, but by the applica- 

 tion of bone-manure, &c., at intermediate periods, to restore to the land those other 

 ingredients which had been abstracted from it in too large a quantity. 



To determine what materials are wanting, and in what proportions they ought to 

 be applied (independently of the empirical plan of ascertaining by repeated trials 

 the substances which by their addition succeed best in remedying the deficiency), 

 two methods present themselves. The first, a difficult one, is to learn, by a minute 

 analysis of the soil, whether the ingredients which the crop requires are actually 

 present, and to add of these a quantity equal to that which the intended crop is cal- 

 culated to contain. The second, a more practical scheme, is to estimate, in the first 

 place, how much of these substances exists in the crop taken off the ground, and 

 then to add to it at least an equivalent quantity in the shape of manure. 



The Professor suggested, that a kind of book-keeping should be undertaken in 

 farming establishments on this principle, a debtor and creditor account being made 

 out, of the quantity of nitrogen, of earthy phosphates, of alkali, &c., abstracted in 

 the foi-m of crop, and restored in that of manure each year. 



He then concluded the paper by specifying certain points relative to this subject, 

 which seem to require further investigation : 



1st. To confirm or disprove his theory with respect to the operation of the nitrates, 

 by determining whether they actually diminish in quantity, and finally disappear, 

 after several successive crops have been grown upon land impregnated with these 

 salts. 



2ndly. Whether the same explanation applies to the agency of common salt and 

 other mineral manures as to that of the nitrates, or whether any of them act directly 

 as stimuli. 



3rdly. More extended and exact data relative to the amount of alkaline and earthy 

 salts, as well as of nitrogen, present in the various crops cultivated by the farmer, 

 as well as in the manures he employs. 



On the Disintegration of the Dolomitic Rocks of the Tyrol. Bi/ Prof.DAVBEJ^v. 



The author attempted to explain, without resorting to volcanic agency, the abrupt 

 form, extraordinary height, naked outline, and fissured surface of the dolomitic 

 rocks in the Tyrol. He attributed the above circumstances to the slow rate at which 

 decomposition proceeds in rocks consisting of pure dolomite, and to the strength of 

 cohesion which binds together the particles of this rock, owing to which, even those 

 portions which stand prominent, in consequence of the removal, by the agents of de- 

 struction, of their contiguous parts, often remain unaffected by the mechanical forces 

 which would cause the projecting portions of a rock less unyielding in its texture 

 to become detached. The cause therefore of the greater height which is maintained 

 by the dolomites of the Tyrol than by the pyroxenic rocks which accompa.ny them, 

 seems to be the inferior rate at which decomposition has proceeded in the former, 

 whilst the bold and jagged outline they display may have been produced by the 



