376 Proceedings of the Royal Society of Edinburgh. 



to regulate the arrangement of the planets and satellites. Bode 

 long ago proposed an empirical law, which he thought regulated 

 the distances of the planets from the sun ; namely, that their dis- 

 tances form a series, increasing by the successive powers of the 

 number 2. Mr Paterson has propounded another similar law, in 

 regard to their sizes ; namely, that throughout the planetary sys- 

 tem there is a regular alternating increase and decrease in size, as 

 the planets increase in distance from the sun, or the satellites from 

 the planets they accompany : that there is a progressive increase 

 from the first to the third, a decrease from the third to the fifth, an 

 increase, again, from the fifth to the seventh, and again a decrease 

 from the seventh to the ninth. He illustrates this supposed law by 

 referring to the respective masses of the planets, and of the satel- 

 lites of Jupiter and Saturn ; and he observes, that, in order to bring 

 the whole solar system under the law, it is necessary that two new 

 planets be still discovered between Mars and Jupiter. 



The law thus conceived to exist, is deduced empirically alone; 

 no reason is assigned why it ought to be observed in the constitu- 

 tion of the solar system. 



2. Notice regarding the Composition and Properties of cer- 

 tain Concrete Juices, resembling Gamboge. By Dr 

 Christison. 



This notice is intended as a supplement to the observations read 

 last session by the author, on the composition and sources of the 

 different kinds of Gamboge. It is well known that Linnaeus re- 

 ferred gamboge to the Garcinia cambogia, Willd. ; and others have 

 supposed that a kind of gamboge is also produced by the Xantho- 

 chymus pictorius. Both are natives of Ceylon, where, as appears 

 from the former investigations of the author, a substance is pro- 

 duced almost or absolutely identical with Siam gamboge. It ap- 

 peared, however, from tHfe inquiries of Dr Graham, read before 

 the Society last session, that this Ceylon gamboge is produced by 

 an undescribed species of tree, and not by either of the species 

 just mentioned. 



Dr Christison has now been enabled to add to this investigation 

 an account of the composition and properties of the concrete juices 

 of the Garcinia cambogia and Xanthochymus pictorius, which were 

 transmitted from Colombo by Mrs Colonel Walker. These con- 

 crete juices, which were sent attached to the barks that produced 

 them, differ from gamboge in having a much paler yellow colour, 



