735 



centres ; which centres are, m their turn, shown to be liberally sup- 

 plied with blood-vessels capable of influencing the galvanic equili- 

 brium. The accelerated respiration caused by increased muscular 

 exertion is attributed to this cause. It is inferred, that the involun- 

 tary muscles are provided with apparatus within themselves, adapted 

 to regulate their periodical galvanic discharge. The mutual reaction 

 of distant parts is attributed to the fact of the whole body being 

 included in one galvanic circle, which cannot be disturbed in a part 

 without the whole participating proportionally in the effects. 



February 10, 1848. 

 The MARQUIS OF NORTHAMPTON, President, in the Chair. 



"Examination of the Proximate Principles of the Lichens." By 

 John Stenhouse, Esq., Ph.D. 



The author, after adverting to the labours of Robiquet, Heeren, 

 Dumas, and Kane in the investigation of the proximate principles of 

 the lichens, especially of those which yield red colouring matter with 

 ammonia, and also of the more recent inquirers on this subject, such 

 as Schunck, Rochleder, Heldt and Knop, who have greatly extended 

 our knowledge of this interesting but difficult department of organic 

 research, proceeds to state that nearly two years ago his attention 

 was directed by Dr. Pereira to a kind of Orcella weed, which had 

 been recently imported into London from the Cape of Good Hope, 

 but which had been rejected by the London archil manufacturers 

 as being unfit for their use, from the small quantity of colouring 

 matter it yields when subjected to the usual process. With a view 

 to ascertain whether or not the red dyes obtained from the various 

 lichens result from the action of ammonia on a certain crystalline 

 principle, described by Schunck under the name of lecanorine, the 

 author procured quantities of the several lichens usually employed 

 by the archil makers, and subjected them to investigation ; the minute 

 details of which, together with the results, are given at length in the 

 present paper. 



The specimens examined are the following ; — ■ 



I. South American variety o/Roccella tinctoria. 



The lichen was cut into small pieces and macerated with a large 

 quantity of water for some hours, then quick-lime was added. A 

 yellow solution was obtained, from which muriatic acid precipitated 

 the colouring matter, as a bulky gelatinous mass ; this was washed, 

 dried on a plate of gypsum, and dissolved in hot spirits of wine (not 

 boiling). The solution on cooling deposited the colouring principle 

 in small white prismatic needles arranged in stars. This is — 



1. Alpha- Or sellic acid (hydrated) C32H15 Oig-f-HO 



and its salt of baryta — 



Alpha- Or selliate of baryta C32H15 Oig-j-BaO 



