74 



bottles of samples of exi^erimeTitally grown veget.ible prodnce, of ani- 

 mal products, of asbes, or of soils, besides some thousands of samples 

 not in bottles." Dr. J. H. Gilbert has been associated with Sir John 

 since June, 1843, and has had charge of the laboratory'. The number 

 of assistants and other helpers has been increased from time to time. 

 During the past twenty five years the working staft" has consisted of 

 from one to three chemists and two or three general assistants employed 

 in routine chemical work and in carrying out the details of field and 

 feeding experiments. A botanical assistant has also occasionally been 

 employed. Besides these workers, there have been from two to four 

 computers and record keepers, a laboratory man, and other helpers. 

 Chemical work has also been done for the station in London and else- 

 where. In this way Mr. H. Kichtcr, formerly connected with the Koth- 

 amsted laboratory, has made numerous ash analyses of animal and veg- 

 etable products at Charlottenburg (Berlin), Germany, where he is at 

 present located. 



"The general scope and plan of the field experiments has been to 

 grow some of the most important crops of rotation, each separately, 

 year after year for many years in succession, on the same land, with- 

 out manure, with farmyard manure, and with a great variety of chem- 

 ical manures, the same kind of manure being, as a rule, applied year 

 after year on the same plat. Ex|)eriments on an actual course of rota- 

 tion, without manure, and with dillVrent inanuros, have also been made." 



Experiments with diUerent fertilizers on wheat have been made for 48 

 years on 11 acres of land, on barlej' for 40 years on 4^ acres, on oats 10 

 years on three quarters of an acre, on beans for from 27 to 32 years on 

 2\ acres, on clover 29 years on 3 acres, on turnips 28 years on 8 acres, on 

 sugar beets 5 years on 8 acres, on mangel wurzels IG years on 18 acres, 

 on potatoes 6 years on 2 acres, on permanent grass 36 years on 7 acres, 

 and on crops in rotation 44 years on 3 acres. Varieties of wheat have 

 been tested during 15 years on from 4 to 8 acres. ^Vheat has been 

 grown in alternation with fallow for 40 years on 1 acre, and in alterna- 

 tion with beans for 28 years on 1 acre. Experiments with various legu- 

 minous plants have also been made during 14 years on 3 acres. Com- 

 parative experiments with dillerent manures have been conducted on 

 other kinds of soils in other localities. 



" Samples of all the experimental crops are taken and brought to the 

 laboratory. Weighed portions of each are partially dried at 100^ C, 

 the dry matter determined, and then burnt to ash on platinum sheets 

 in cast-iron muffles. The quantities of ash are determined and recorded, 

 and the ashes themselves are preserved for reference or analysis. 



" In a large proportion of the samples the nitrogen is determined, and 

 in some the amount existing as albuminoids, amides, and nitric acid. 



