By Mr. William Hedges. 



175 



according as T placed them in garden compost, or in the yel- 

 low loam of Hampstead Heath. If a plant whose flowers 

 had been red one year, was shifted into the loam, they be- 

 came bine ; if the plant remained i \ the loam a second year, 

 the flowers continued to be blue, but if it was returned to the 

 garden compost, whether after one or two years, it resumed 

 the red colour of its flowers. It was conjectured that a su- 

 perabundance of iron in this loam might cause it to produce 

 this change in the plants, and this conjecture was strength- 

 ened by an account, that a small quantity of filings of iron, or 

 steel, mixed in any soil in which Hydrangeas grew, would 

 make them vary the colour of their flowers. To ascertain 

 the accuracy of this account, I last winter planted several 

 Hydrangeas in various soils, into which I put a small quantity 

 of iron filings ; others I planted in bog earth, others in garden 

 compost, and some in the Hampstead Heath loam ; but I ob- 

 tained blue flowers from the last only, I therefore place no 

 reliance on the efficacy of steel or iron filings, nor do I sup- 

 pose that iron can be the agent in the change, since mould 

 which contains as much iron as that of Hampstead Heath is 

 useless for this particular purpose. It cannot be questioned 

 but it is some peculiar quality in the earth, which produces 

 this singular effect ; what it is, I have not been able to ascer- 

 tain ; all I can do is to give the results of my experiments, 

 which are, that no adventitious matter, yet named, will effect 

 the change wi th certainty ; that garden mould or compost 

 will invariably keep the flowers red; that some sorts of bog- 

 earth will make the flowers blue, as is the case in the Dalston 

 garden, but that every sort of bog-earth will not ; and lastly, 

 that the sort of yellow loam, I have described, will invariably 

 produce the change. 



