110 Botany and. Agriculture. 



were inverted over a common pneumatic apparatus, arid! 

 oxygene gas introduced till a third or fourth part of the 

 water was difplaced : the bottles being then flopped, were 

 agitated for fome time till it was believed the water had taken 

 up all the gas that it could receive. 



We know not whether the rcfiduum of the gas has vet 

 been fubmitted to any te(t, to determine whether it under- 

 goes a change hv being thus warned by the water; but, no 

 doubt, the fubjcel will receive that attention which it merits 

 from thofe who have the means and opportunity of repeating 

 and following out the experiments. 



It appears to be a fubjeet worthy of enquiry, what would 

 be the belt and eafieft methods for impregnating water with 

 oxygene ? or, which would be perhaps (till better, what 

 would be the beft fubftance to be thrown upon land to ena- 

 ble it, or the moifture it contains, to abforb the greateft quan- 

 tity of oxygene from the atmofphcre ? 



Some experiments have been latclv made in the neigh- 

 bourhood of Briitol, under the immediate infpcAion of one 

 of the members of the Bath Agricultural Society, with re- 

 fpect to the culture of madder; the refult of which is, that 

 madder may be produced in large quantities in England, and 

 fold to the dyers at a cheaper rate than that imported, being 

 of a quality equal to that grown in Zealand. In 1756 the 

 king of France iflucd an edict, exempting from land-tax 

 for the fpace of 20 years (that is to fav, in all fields newly 

 broken up) all cultivators, of madder in drained marines and 

 other waftc and neglected grounds. In 1762 the Board of 

 Agriculture held ?X Bcauvais made it plain to all perfons 

 concerned in dyeing, that madder raifed in that diftrict, and 

 Aifed while the roots were frefh gathered, gave a finer tinc- 

 ture than the Zealand madder, and went further in the pro- 

 portion of eight to five. In the fame year it was ordered in 

 council, that no tax, for the fpace of 20 years, fhould be 

 levied upon grounds newly broken up, provided the faid 

 grounds had lain 20 years in an, uncultivated ftate. In 1761 



there 



