48 Royal Society. 



elusion, that during the slow combustion of phosphorus in moist 

 atmospheric air, while ozone is produced, there is also formed a 

 quantity of nitric acid ; and that in all cases where both these com- 

 pound bodies are simultaneously generated, however different may 

 be the concomitant circumstances of the experiment, there is strong 

 reason to suspect that the formation of the one is in some way con- 

 nected with that of the other. 



" On the Process of Etching, or Engraving, by means of Voltaic 

 Electricity." By James H. Pring, M.D. Communicated by P. M. 

 Roget, M.D., Sec. R.S. 



The author, referring to an account which he gave of his method 

 of etching on hardened steel plates, or other polished metallic sur- 

 faces, by means of Electricity, in the Philosophical Magazine for 

 November 1843, offers some additional observations relating to the 

 theory of the process, and states some further practical remarks in 

 its application to engraving. A specimen of a steel plate, and of a 

 razor, on which ornamental designs were engraved by this method, 

 were laid before the Society, in illustration. 



February 19. — " On the Mechanism of Respiration." By Francis 

 Sibson. Communicated by Thomas Bell, Esq., F.R.S. 



This paper is almost entirely occupied with anatomical details, 

 collected from an extensive series of dissections of the muscles and 

 bones concerned in the act of respiration in man and the lower ani- 

 mals, for the purpose of elucidating the mechanism of their action 

 both in inspiration and in expiration ; accompanied by a great num- 

 ber of illustrative diagrams and drawings. The author commences 

 with the serpent tribes, which present the simplest form of ribs, 

 being attached only at their vertebral ends, while their anterior ends 

 are free. When these ribs are brought forwards by the action of 

 the levatores costarum and external intercostal muscles, the chest is 

 expanded ; and when drawn backwards by the long depressors, in- 

 ternal intercostals and transversales, expiration is effected. In birds 

 there are added to the former apparatus a sternum, and a series of 

 sternal ribs, the respiratory movements of which are performed in 

 directions the reverse of those of the vertebral ribs. During inspi- 

 ration, the angles between the vertebral and sternal ribs become 

 more open ; the sternum moves forwards, and the spinal column 

 slightly backwards, by the combined action of the scaleni and 

 sterno-costal muscles on the first vertebral and first sternal ribs re- 

 spectively ; of the levatores costarum and external intercostal on all 

 the lower vertebral ribs, and of the sternal intercostals on all the 

 lower sternal ribs. On expiration these movements are reversed by 

 the action of the internal intercostals, the external and internal 

 oblique, recti, transversales and other muscles. The mechanism in 

 the Mammalia is further assisted and modified by the addition of a 

 large and powerful diaphragm. The thoracic ribs are articulated 

 with the sternum by the medium of cartilages corresponding to the 

 sternal ribs of birds : those ribs which are connected with the infe- 

 rior curve of the dorsal arch have floating cartilages, and may be 

 considered as a diaphragmatic set of ribs. When raised, the former 



