CHEMICO-AGRICULTURAL TOUR. ;I29 



afford the most convincing proof of the correctness of the views 

 entertained by those gentlemen relative to the necessity, in the 

 practical application of manures, of having nitrogenous matter 

 (capable of furnishing ammonia, nitric acid, or some other assimi- 

 lable form of nitrogen), in addition to the mineral substances 

 required by plants, in order that the vegetables we cultivate may 

 grow with the greatest luxuriance, and yield the most remunera- 

 tive crops. Dr. Gilbert also showed me, in the park at Rotham- 

 stead, some very interesting effects of different manures, when 

 applied for several years to permanent meadow land, which is a 

 subject of much practical importance. Some of those effects which 

 I saw were the following ; that where a mixture of purely mineral 

 manures had been applied, the principal effect was to develop and 

 increase the growth of the leguminous plants contained in the 

 meadow land ; but it had scarcely any effect in promoting the 

 growth of the graminaceous plants, or natural grasses. Where, 

 on the other hand, purely nitrogenous manures — as, for example, 

 ammoniacal salts, or nitrates — had been applied, their effect was 

 to increase the growth of the natural grasses, and rather to dis- 

 courage the development of leguminous plants. But whore a mix- 

 ture of both mineral and nitrogenous manures was used, the 

 growth and produce of the natural grasses were greater than when 

 each kind of manure had been employed separately; while, at the 

 same time, the mineral manures, when in combination with the 

 nitrogenous, did not, as when used alone, produce the same effect 

 in developing the leguminous herbage. 



These effects, which Mr. Lawes and Dr. Gilbert have already 

 pointed out in some of their many important contributions to sci- 

 entific agriculture, were most strikingly evident by a mere inspec- 

 tion of the different experimental plots. I was also shown at 

 Rothamstead different ingenious arrangements the same gentlemen. 

 had adopted in carrjnng on some very interesting experiments they 

 were engaged in, relative to the feeding and nutrition of animals. 



I took an opportunity, before leaving London, to visit the labo- 

 ratory of the Royal College of Chemistry, as well as that of Mr. 

 Wa}', where I saw several new forms of apparatus, affording in- 

 creased facilities in chemical research. I also went to the museum 

 at South Kensington, and was much pleased with its very interest- 

 ing " Food Collection," which exhibits the proximate and ultimate 

 constituents of the most important articles of our food in a very 

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