18 



NUTRITION OF VEGETABLES. 



the roots, to remove any portions of oxide of lead, and wiped 

 them dry* the whole weighed 264 gr. After thej were dried, 

 the weight was 34*2 gr. 

 The produce These yielded 12 gr. of coal, which by incineration were 

 analysed. reduced to 4'2 gr. of ashes. These lost by lixiviation 2*2 



gr. ; of which '59 gr. were sulphate of potash, '6g gr. pot- 

 ash. The insoluble residuum aftbrded '4 gr. of silex; '45 

 gr. of oxide of iron, alumine, and phosphate of lime, the 

 proportions of which were not determined ; '57 gr. of ox- 

 ide of iron ; and a very small portion of magnesia. 

 Mustard seed Exp. II. In a very large, deep, and perforated bowl of 

 of sulphur. stone ware, filled with well washed flowers of sulphur, 250 

 seeds of white mustard were sown. The whole was covered 

 with a large bell glass, allowing free access to the air and 

 light. The plants grew vigorously, being frequently wa- 

 tered with distilled water ; as sulphur, having little affinity 

 with water, parts with it very easily, and dries on the sur- 

 face. They produced flowers in tolerable abundance, and 

 The produce the seeds produced plants in common groimd. The weight 

 analysed. ^^ ^^^ f^,^^^ plants, with the fallen leaves, was 108 gr. ; and 



when dried 18*6 gr. Their coal weighed 7*8 gr. and left 

 1*55 gr. of whitish ashes, which aflbrded by lixiviation '6 gr. 

 of carbonate and sulphate of potash. The insoluble part was 

 similar to that of the former. 

 Mustard seed Exp. III. A hundred seeds of white mustard were sown 

 sown m small ^^ twenty pounds of very smaU unglazed shot, on the 9th of 

 July. On the 28th of August they began to flower, and 

 aflbrded small pods. All these plants were slender, and had 

 but few and small leaves. When fresh they weighed 10 gr. 

 and after being dried 2*3 gr. they yielded very little coal, 

 but more than the weight of the seed. The weight of the 

 shot appeared to oppose too great an ebstacle to the young 

 roots, as most of them spread over the surface, without 

 being able to penetrate it. The iittle affinity of the lead for 

 water was another reason of the feeble growth of the plants ; 

 and hence I have found, that plants thrive less in metallic 

 powders, than in their oxides. 

 Radish seed Exp. IV. On a flat stone pavement a bed was formed, 



s.mn in aheap ^^^^^ a yard hit;h, of fine sand, taken immediately from 

 of sund, . o ' .' 



the bed of the river, and well washed. In this were sown 



seeds 



