410 



Dr. J. Stenhouse on Nitro-suhstitution [Mar. 30, 



separate pieces at work in a deep hollow, close together, and attached to 

 delicate arteries, none of which could be permitted to twist or interfere 

 with each other. I append a reduced sketch of 

 one of the two frameworks over which, as pre- 

 viously described, I suspended these instruments, 

 with attached counterpoises, and so avoided all con- 

 fusion. Both pair of canulae and two pair of 

 forceps are here represented ; they might be so 

 arranged ; but it is better to divide the instruments, 

 equally, between the two frames. 



For removing clogs from the canulse, I tried a 

 great many plans, none with as much success as I 

 could wish. I have, however, been able to extract 

 clots from the artery itself, a good quarter of an 

 inch beyond the canulae, with a wire whose end had 

 been cut with a file into a delicate solid corkscrew. 

 I washed out the canulae, before reconnecting, with a thin stream of water 

 sent through the quill of a small bird, which I had fastened, by help of a 

 short India-rubber tube, to my syringe. 



The wounds require careful dressing, just like those of a man. The 

 rabbits bear the operations wonderfully well, and appear to suffer little or 

 no pain when the influence of the anaesthetics happens to have left them 

 temporarily sensible. They are often quite frisky when released, and 

 sometimes look as though nothing whatever unusual had happened to 

 them, all through the time of their recovery. 



II. " Contributions to the History of Orcin. — No. I. Nitro-substi- 

 tution Compounds of theOrcins"*. By John Stenhouse, 

 LL.D., F.R.S., &c. Received March 1, 1871. 



The action of nitric acid upon orcin has been studied by several chemists, 

 but with comparatively negative results. Schunck f in this manner ob- 

 tained a red resinous substance, which by further treatment with the acid 

 was oxidized to oxalic acid ; and in 1864 DeLuynes % found that orcin dis- 

 solved in cooled fuming nitric acid without evolution of nitrous fumes, 

 and that the addition of water precipitated a red colouring-matter ; the 

 long- continued action of the vapour of fuming nitric acid on powdered 

 orcin likewise produced a red dye apparently identical with the above. 

 These, however, were resinous uncrystallizable substances. 



Although under ordinary circumstances only resinous products are ob- 

 tained by treating orcin with nitric acid, yet, when colourless orcin in fine 



* A Preliminary Notice with this title was published in the ' Chemical News,' 

 August 26, 1870. 



t Ann. Chem. Pharm. vol. liv. p. 270. J Ibid. vol. cxxx. p. 34. 



