I shall only add, that Mr. Simson’s son, who is now minister at Fala, was present at the opening of the body, and can attest, that there was no stone found in the bladder. Adam Austin. Edinburgh, 15 April 1757. _A Letter from Dr._ Adam Drummond _to Dr._ Adam Austin, _relating to the Rev. Mr._ Matthew Simson’_s Case. Communicated by_ J. Pringle, _M.D. F.R.S._ [Read June 23, 1757.] I Have yours; and was present when Mr. Balderstone sounded Mr. Simson; and both of us perceived, very distinctly, a large stone: and Mr. Simson himself felt it; which we were the more sollicitous he should do, as he was sounded before by Dr. Simson, who had declared there was no stone. But the particular magnitude of it we could not well determine at the end of a long catheter; tho’ I remember Mr. Balderstone, who was well versed in that business, conjectured it to be pretty large. He was sounded only once by us, as the urethra was a little hurt by turning the catheter. There is only one circumstance in the case, which Mr. Simson seems to have omitted; that, from the first symptoms of the stone, he passed a great deal of _mucus_ mixed with _pus_, as well as blood; and great quantities of gritty red sand, all in single grains, never any concreted into small stones. I take the more notice of this, as I do not remember, that, after he used the soap, he ever passed any sand, but a good deal of _mucus_, in which the soap was discoverable by its frothing. Could the gritty particles of sand be again suspended in the urine, so as to become invisible? or were they wrapt up in the soapy liquid, so as to escape observation? I have seen several stones of a soft consistence dissolved into mucilage by soap: but the sand passed by Mr. Simson, before he used the soap, seems to indicate his stone of a harder nature, tho’ indeed it felt obtuse at the end of the catheter. I shall rejoice, if many instances of this kind are found afterwards: but this seems to be the only one yet, of a stone in the bladder being dissolved by soap alone. I am, Dear Doctor, Your most humble Servant, Adam Drummond. Bandeeran, June 5. 1757. XXVIII. _An Account of the Impressions of Plants on the Slates of Coals: In a Letter to the Right Honourable_ George _Earl of_ Macclesfield, _President of the R.S. from Mr._ Emanuel Mendes da Costa, _F.R.S._ [Read April 28, 1757.] My Lord, I Have the honour to address this letter to your Lordship, in order to be communicated to the Royal Society, if your Lordship deems it worthy the attention of that learned and illustrious assembly.