potatoes, for it was on potatoes he experimented. The potatoes 

 were planted on the 3d of May 1 832. 



1. On the first plot of the experimental field, 28 Ib. of white potatoes were planted in 

 two rows, and the ground manured with farm-yard manure. 



2. On the second, 28 Ib. of the same potatoes were planted, and the ground man- 

 ured with 139 Ib. of burnt clay, and the same quantity of manure as that applied on 

 the first plot. 



3. The third received 130 Ib. of burnt clay only, and the same quantity of pota- 

 toes, (28 Ib.) 



4. On the fourth plot, 28 Ib. of the same potatoes were grown without any man- 

 ure whatever. 



The produce was collected on the 27th of September, and gave 



1. 278 Ib. of full-grown potatoes, with but few small ones. Some of the larger 

 weighed from 54 to 6| ounces ; the weight of most was 2 to 3 ounces. 



2. 280 Ib. of equally good potatoes. Some of the larger weighed 6 to 8 ounces. 

 There were few under 1 ounce. 



3. 276 Ib. of perfectly matured, very good potatoes. Most were middle-sized, of 3 

 to 4 ounces weight, with but few small ones. 



4. 127 Ib. only of potatoes, of a scarcely mediocre quality, mixed with many small 

 ones which had not come to perfection. The plants produced only a few seeds, 

 whereas the potato plants in No. 3. furnished even a greater abundance of seed- 

 apples than those planted in No. 1. 



In comparison with the seed-potatoes, the produce of the four plots was therefore 



1. In the field manured with farm-yard manure, ten-fold. 



2. In the field manured with farm-yard manure and burnt clay, nearly eleven-fold. 



3. In the field manured with burnt clay only, nearly ten-fold. 



4. In the field without manure, only a little more than four-fold. 



In these experiments, the highly profitable effects of burnt clay on the potato crop, 

 grown on perfectly exhausted land, are exhibited in a most convincing manner. 



Passing over the details of the subsequent chemical analyses, to 

 which not only the tuber, but likewise the roots, stem, leaves, and 

 seeds of the potato plants were subjected by Lampadius, the fol- 

 lowing are the ultimate results at which he arrived: 



a. Burnt clay benefits the growth of potatoes on the poor loam of the neighbour- 

 hood of Freiberg nearly as much as mixed animal and vegetable manure, (common 

 farm-yard manure.) 



6. The tubers of the potato plants furnish the same quantity of starch, fibre, and 

 water, whether they be grown with farm-yard manure or with burnt clay. 



c. The seed-apples, roots, stems, tubers, and leaves of the potato plants, contain the 

 same inorganic constituents, and in the same relative proportions, when grown with 

 burnt clay or with farm-yard manure. 



d. The amount of inorganic matters in the different parts of the potato plants dif- 

 fer very considerably. 



In order to give an idea of the spirited manner in which Lam- 

 padius carried out similar experiments, I would draw the attention 

 of the reader to the fact that, in the same year, this indefatigable 

 philosopher tested the effects of burnt clay on no less than twenty 

 different crops, in a manner which proved forcibly the economic 

 value of this kind of manure. He further caused many farmers 

 to try experiments with burnt clay on a large scale, and had the 

 satisfaction to see his own experiments confirmed by the experi- 

 ence of many practical farmers. So successful, indeed, were nearly 

 all his experiments, and so much the interest of the agricultural> 

 community of Germany excited by Lampadius's labours, that, by 

 command of the Government, public establishments were erected 



