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VIII. On the Use of Green Vihrlol, or Sulphate of Tro7tf 

 as a Manure; anil on the Efficacy of paring and burning 

 depending parfhj on Oxide of Iron. By Gkorge Pear- 

 son, M.D. lionorari/ Member of the Board of Agri- 

 culture, F.R.S. &c.'c^c.&c*' 



X TAKE leave to lav before this honourable Board an ac- 

 count of a substance as a manure which I find, on exa- 

 mination, is one of the things hitherto universally believed 

 to be a poison to vegetables. Having ascertained that this 

 substance is what is commonly known bv the name of vi- 

 triol of iron (the sulphate of iron of the chemists), invete- 

 rate opinion prevented me for some time from accepting 

 the testimonv of it as a manure ; but feeling the weight of 

 the respectable evidence bv whom it was attested, after 

 consideration I perceived that the fact in question was not 

 at variance with established principles of vegetable philo- 

 sophy, as I shall, I think, make appear in this communi- 

 cation. 



My friend .Tohn Williams Willaume, esq. ofTingrith, 

 in Bedfordshire, having desired his brother, Charles Dy- 

 moke Willaume, esq. to ask my opinion of a saline sub- 

 stance collected from peat, which has been used w ith pro- 

 fitable consequences as a manure in his neighbourhood, I 

 proposed a set of queries to Mr. John W. Willaume, the 

 answers to which, in the two following copied letters, com- 

 prehend the evidence 1 have to offer. 



Letter No. I. — To Dr. Pearson, from C. D. JVillaume, 

 Esq. 



MY DEAR SIR, 



I received the inclosed last Saturday, and hope the an- 

 swers to your queries will. be satisfactorv, and tend to elu- 

 cidate this curious subject. Though the answers under the 

 article dust ordy relate to your queries, yet my brother has 

 thought proper to advert to the ashes, which you conceive 

 to be a caput mortuum ; but which have been used as, and 

 have been supposed to be, a beneficial manure from time 

 immemorial. I have reserved a piece of the peat from which 

 the ashes are produced, and if you would wish to analyse it, 

 I will send it you. Favour me with the result of your fu- 

 ture inquiries on this subject ; and I am, 



My dear sir, yours very sincerely, 

 Walham Green, C. D. WiLLAUME. 



Aug. 24, 1801. 



* A communication to the Board of Agriculture. 



Letter 



J 



