Mr. Carty on a Specimen of diseased Wheat. 189 



a spiral course; they originate in a movement which takes 

 place in the mercurial globule, a movement which is well 

 known to be connected with the presence of small quantities 

 of certain metals. Tiie path of these currents is determined 

 by the figure of the mercurial globule; their existence by the 

 unequal pressures exerted upon its various parts. 



If we suppose thus that capillary attraction is only a mani- 

 festation of electric disturbance which takes place on the con- 

 tact of bodies, we obtain the advantage of assigning a distinct 

 physical cause for an extensive class of facts. We replace an 

 unknown and hypothetical agent by one with the qualities and 

 laws of which we are familiar; and we bring the phaenomena 

 in (juestion into a very interesting relation with those of che- 

 mical affinity; for, recollecting Clairaut's law, which deter- 

 mines the position of a liquid in a tube, "that if the double of 

 the action of the matter of the tube is greater than the action 

 of the liquid upon itself, there is an elevation ; if the two quan- 

 tities are equal, the hydrostatic level is maintained ; if the 

 former is less than the latter, there is a depression ;" and con- 

 necting this with the well-known law of chemistry, "that if 

 the attraction of the particles of a liquid for those of a solid is 

 greater than the attraction of the particles of the latter for one 

 another, solution of that solid ensues," we are led at once to 

 see that the phaenomena of capillary attraction stand in a sin- 

 gular relation to those of chemical affinity. They are exam- 

 ples of facts belonging to the same physical class. The adhe- 

 sion of a dye to cloth-fibre, or of the amalgam to the back of 

 a mirror, are merely instances of the general electro-chemical 

 relations of matter*. 



XXI. Examination of a Specimen of diseased Wheat. 

 By Mr. J. CARTyf. 



IVI Y attention was lately directed by Mr. Briggs, of Over- 

 -^*-*- ton, near Wakefield in Yorkshire, to a kind of disease 

 which he considers to be burnt- ear, and analogous to smut, 

 which had attacked some wheat growing on his land. The 

 stalk of the wheat was of the usual height and strength, and 

 the ears seemed externally healthy ; but on breaking into the 

 grain it was found to be filled with a black powder, instead of 

 the white, thick juicy substance found in healthy wheat at the 



* On the adhesion of a dye to cloth-fibre, see Phil. Mag., S. 3. vol. xxiv. 

 p. 241 ; and we ma}' also refer Dr. Draper to a discussion by Prof. Challis 

 and Mr. Brayley, on the relations between the attraction of aggregation 

 and chemical affinity, bearing immediately on the subject of his paper, in 

 Phil. Mag. S. 3. vol', viii. p. 94, 172, 288.— Edit. 



t Communicated by the Chemical Society ; having been read November 

 4, 1844. 



