290 



also unite with three quantities of oxalic acid ; but it was found, that 

 when two parts of potash are in solution with six equivalent quanti- 

 ties of oxalic acid, they do not crystallize together in this proportion ; 

 but one part of the potash becomes a true binoxalate by union with 

 two parts out of the six of oxalic acid taken ; and the other part of 

 potash is found united with the remaining four parts of acid. 



The author expresses an opinion that we shall not be able to ex- 

 plain satisfactorily, why this acid refuses to unite in the proportion 

 of 3 to 1, till we can attain a just conception of the geometrical ar- 

 rangement of the elementary particles in all the three dimensions of 

 solid extension. It being supposed, for instance, that the particles 

 are spherical (which is the simplest hypothesis), if they unite 1 to 1, 

 there is but one mode of union. If 2 particles are united to 1, the 

 2 particles will arrange themselves at opposite poles of that to which 

 they are united. If there be 3 particles, the only regular position 

 in which they could remain is in the form of a triangle in a great 

 circle surrounding the single spherule ; but for want of similar mat- 

 ter at the poles of this circle, the equilibrium would not be stable. 

 But again, if there be 4 to 1, a stable equilibrium would occur, when 

 they assume the form of a regular tetrahedron, surrounding the single 

 particle. 



But as the author does not place much reliance on this explanation, 

 since such a geometrical arrangement of the primary elements is 

 altogether conjectural, he is desirous that it should not be confounded 

 with the results of the facts above related, which are distinct and 

 satisfactory with respect to the existence of the law of simple mul- 

 tiples. 



On the Inconvertibility of Bark into Alburnum. By Thomas Andrew 

 Knight, Esq. F.R.S. In a Letter to Sir Joseph Banks, K.B. P.R.S. 

 Read February 4, 1808. {Phil. Trans. 1808, .p. 103.] " 



Mr. Knight having on a former occasion observed the bark of trees 

 to originate from a fluid exuding from both bark and alburnum, con- 

 tinues the subject by observations, tending to prove that bark thus 

 formed always remains in the state of bark, and that no part of it is 

 ever converted into alburnum, as various eminent naturalists have 

 maintained. 



Equal portions of bark from several branches of an apple and a 

 crab-tree were removed by circular incisions, and transposed from 

 tree to tree in the spring ; and a vital union was secured by bandages, 

 and by a plaster of bees' wax and turpentine. 



When some pieces of bark were removed in the autumn of the 

 same year, a layer of alburnum was found to have been formed be- 

 neath them in every instance ; that of the crab-tree having the colour 

 and roughness of the stock on which it was produced, while that of 

 the apple-tree showed none of the sinuosities of the bark of the crab- 

 tree which covered it ; neither did the vessels and fibres of the newly- 

 generated alburnum in any degree correspond with those of the trans- 



