Influence of Soils on Plants. 405 



be defeated by the presence of other inherent matter; for 

 though it was inactive over the cold soil, it acted in full force 

 upon the soil, when, by roasting, it had discharged its gas. 



Hydrangea hortensis. — While a profitable experiment 

 resulted on the one hand, a great amusement occurred on the 

 other, with some green-house plants. I mixed the compost 

 fresh from the ditch, with water, and found a precipitation of 

 iron : I used the soil and water to a hydrangea, a cutting from 

 the common pink variety, and it so altered the colour to 

 purple, as to form a ?iew plant. I applied the same to the 

 Canna indica, and some other scarlet and blue plants, but 

 obtained no apparent change of colour. I have always con- 

 sidered the brilliancy of colour to depend upon the air-bubbles 

 under the epidermis of the petals, and was much surprised at 

 not having effected a change in the Canna. though the colour 

 will change under strong rays of soiar light. Pink and purple 

 flowers may be more sensible of the influence of the gas, 

 being secondary colours, than the red and blue, which are 

 primary. 



This district is upon freestone ; the adjoining is limestone : 

 upon the line of junction are the wild flowers indigenous to 

 both soils, and it is wonderful to see the brilliancy of the 

 colour of them upon the latter, in comparison of the former. 



I do not know whether or not the above experiments are 

 new to you or your readers ; if new, they may afford security 

 to operative melon growers, and amusement to florists. The 

 subject is very interesting to myself and some other botanical 

 friends here. I am no chemist, but if your correspondents can 

 elicit any information from that science, I think they will add 

 much to vour valuable work. 



Sheffield, May, 1826. W. R. Y. 



There is a fine opening in horticulture for any chemist of 

 leisure, and practical acquaintance with the various operations 

 of garden culture and management, to exert and distinguish 

 himself. The good and the evil of pulverising soils, and 

 exposing them to the atmosphere, and to different descriptions 

 of weather, remains to be determined, no less than to be 

 explained. It may excite surprise in some gardeners to be 

 told that ridging of garden soil, in order to expose it more 

 completely to the influence of either frost or sun, is fre- 

 quently more injurious than useful ; but we believe the asser- 

 tion is consistent with facts, and with the experience of accurate 

 observers. If bad qualities are exhaled, or oxidised by the 

 aeration of soils, may not good qualities also escape or undergo 



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