ON' THE ITOOD OF PLANTS. 



II. 



On the Food of Plants, by the Rev. Joseph TownsAend, 

 Rector of Pewsey, Wilts*. 



HAT is the food of plants ? Before we can give a sa- Seeds vegetal* 



tisfactory answer to this question, we must collect facts; we rapidly in oxi- 



11 t-< i • ■ iL gen; and not 



must multiply experiments, r or this purpose, in the years at a u - in n n Ti ^ 



1702 and 1793 I put various seeds to vegetate in different gen- 

 airs; m atmospheric air, in vital air, and in azote. The ge- 

 neral result was that neither wheat, oats, nor barley, vegeta- 

 ted in azote; but in vital air vegetation was uniformly rapid. 



July 12, 179o\ I placed eleven cabbage-plants in pots, all Cilbba?c 

 healthy plants, and weighing each f ounce apothecaries' plants, 

 weight. The pots stood in pans with water, and remained 

 in them till June 12, 1797, when the plants were taken out 

 of the pots and weighed again. 



Of these pots four had quartz sand, washed clean, and 

 rendered perfectly free from mixture of either argil or cal- 

 careous earth. 



No. 1 had nothing but this sand ; the plant lived, but did in P^e quartz 

 not increase in bulk; when examined, the radical fibres ' 

 were found numerous and extended, but very small ; and 

 when the plant was weighed jn January 1797> it had not in- 

 creased in weight. 



No. 2 had the same kind of sand and woollen-rags: the sand and wool- 

 roots shot vigorously, the plant cabbaged, and in January 

 1797 weighed two ounces. 



No. 3 had the same kind of sand, with about $ part char- sand andcharr 

 coal in powder ; the roots were less vigorous than the for- coa * 

 mer, and in January 1797 the plant weighed J ounce. 



No. 4 had this sand with about <£■$ lime. The plant did sand & lime, 

 not increase, yet lived, and in January 1797 weighed only ' 

 3 dwts. having lost |- of its original weight. 



No. 5 had brickmaker's clay alone ; the plant lived, brick clay, 

 looked fresh, but in January 1797 weighed only § ounce. 



No. 6 had brickmaker's clay, with an equal proportion of clay and sand, 



* Bath Society's Papers, tol. X, p. 1. 



the 



