NUTRITION OF VEGETABLES. jl^ 



seeds of the common radish fraphanvs sativnsjy which were 

 fiequtntly watered witli perlectly pure rain water, and the 

 ■plants grew with as mucli vigour as they would have done in 

 any ground. The greater part of the radishes were brought 

 to table, and were of a very delicate flavour, without any 

 of the disagreeable earthy taste they have sometimes. Some 

 of them were left to seed; and most of these grew to the 

 height of 2 feet or 2j. It was observed, that those at the 

 top of the heap were much larger and stronger than those 

 near the bottom*. 



Sixty three of these plants when dried weighed 372 gr. 'Hie produce 

 Incinerated they left 54'2 ^v, of gray ashes. These afforded ^^^'y^ed, 

 by lixiviation 18'6 of very fine potash. From this I am in- 

 clined to think, that the radish might be cultivated with ad- 

 vantage on wet sandy places by the sea shore, for the pur- 

 pose of fabricating potash f. Th<ise 18'"6 gr. being farther 



analysed, 



• A skilful gardener informs me, that asparagus too will succeed very Asparagus and 

 well ill pure river sand. Potatoes also grow well in sand, and are said to potatoes grow 

 be better tasted. ^^^ii in saad. 



•f- It appears, that potash abounds in all the plants of the class tetra- Potash abounds 

 dynamia, and the ashes of some of the species were long in use for in tetradyna- 

 making soap and glass, before the introduction of soda as an article of ^^^^ ^ ^" *** 

 trade. According to Bomare, the bunias cakile, sea rocket, was much 

 employed for these purposes. 



I must here add an observation, which appears to me pretty general, Acrid and bit- 

 and which I made in examining the acrid and bitter properties of plants. ^'^^ plants ge- 

 One or other of these principles 1 have almost always found in con- ^^^^ J^ " 

 junction with a large quantity of potash, which was frequently saturated quently coni- 

 with nitric acid. Thus among the cruciferous plants, which are ail more bined with ni- 

 or less acrid, the sisymbrium nasturtium, common water-cress, afforded ^^^^ ^c\d,. 

 nie a great deal of alkaline matter after incineration j and when frCbh I 

 found in it nitrate of potash. I have observed the nitre melt on incine- 

 rating cabbages and turnips ; and Mr. Delaville found this salt in large 

 quantity ia the sop of these plants. Mr Bouillon-Lagiange found a 

 large quantity of potash in the ashes of the crigeron canadense, Canada 

 fleabane, which is acrid. The ashes of tobacco, the acrimony of which 

 is well known, yield 40 per cent of potash. Among the bitter plants I 

 have examined, 1 found niirate of potash in the fumitory, 100 parts of 

 the a^^hes of which contain more than G6 soluble jn water, according to 

 Wiegleb and Rukert. The common centaury, marsh and Siberian tre- 

 foil, and different species of the genus centaurea, which are very bitter, 

 afford ashes in wVuch potash abounds. Whether in these plants it be 



C ^ saturati'd 



