24 Anatomy of the Vine. 



the liber of the leaf; this fluid may be easily precipitated by 

 simply placing, in the autumn (previously the vessels are so 

 small that they are choaked up by the precipitate), a shoot 

 of the vine, in a weak solution of the sulphate of iron and, 

 upon standing therein for some time, the thin parts of the 

 leaves will become black, as soon as the union takes place 

 between the ascending sulphate of iron, and the gallic acid of 

 the leaf; it will afterwards descend down the vessels of the 

 liber of the stalk of the leaf, and sometimes down to the liber 

 of the collet, which will in like manner become black : but 

 the ascending vessels of the alburnum of the shoot will not be 

 discoloured, nor the ascending vessels of the stalk of the leaf, 

 because the solution has not met with any gallic acid in its 

 ascent through those vessels. 



It is highly gratifying, in our examination of the economy 

 of Nature, to have her assistance in such operation ; for no 

 artificial means could have been used to pass a solution into 

 the above minute vessels had they been void of actual life. 



By the assistance of these chemical tests, I flatter myself 

 the investigation of the anatomy of vegetation will be facili- 

 tated, and I sincerely hope others will prosecute it with greater 

 perseverance ; by so doing they will convince themselves how 

 sublimely Nature carries on her grand operations, by a repe- 

 tition of parts, and those united by the most simple means, as 

 well as by a continuation of those parts subdivided. Although 

 we shall never discover the hidden springs by which she 

 creates, animates, and elongates the living vegetable fibres; 

 yet, by their aid, many interesting facts may be discovered 

 relative to the larger vessels. I have many apologies to make 

 for occupying your time, even in the perusal of this long let- 

 ter ; and I am fearful, also, in addition to the reasons already 

 given of the number of drawings, that the length of my re- 

 marks will exclude both from your valuable and instructive 

 Magazine ; but this I must leave entirely for your liberality 

 and consideration. I remain, Sir, &c. 



Bath, June 12. Walter William Capper. 



The common copperas, or sulphate of iron, becomes a 

 stronger test by the following method : — 



Dry down before the fire, on a plate, 8 oz. of the common 

 copperas of the shops. Reduce it to a fine powder, then weigh 

 100 grs. of it, which place in a mortar, and add to it 10 drops 

 of nitric acid, mix them well together, afterwards add 4 oz. 

 of water, and filter it» This liquor should be kept closely 

 stopped. 



