Intelligence afid Miscellaneous Articles. 235 



done, on looking perpendicularly down upon the reflecting sur- 

 face, at the distance of distinct vision from it (unless the eye be too 

 long-sighted), the powder will appear, not irregularly scattered, as 

 it really is, but symmetrically distributed in two systems of beauti- 

 ful radiations, having the pupils of the eyes for their centres. 



The phenomenon is sufficiently remarkable to strike even those 

 who are not otherwise curious in such matters. It may be observed, 

 however, that as every eye cannot catch it at once, it is better to 

 commence by using one eye only, as this gives only one system of 

 radiations, which, being more simple, is more easily observed. If 

 this phaenomenon has not been already attended to (and I do not 

 recollect to have seen it noticed anywhere), it is, I think, well wor- 

 thy of investigation. Some facts are, indeed, immediately obvious 

 respecting it. Thus, as to the region in which the physical part of 

 the phaenomenon takes place, it plainly appears that it is not either 

 the humours or retina, as is generally supposed in reference to other 

 phaenomena of the same order, but a more deeply seated part of the 

 apparatus of vision. For if it were any of the anterior parts, or even 

 the retina itself, the centre of the radiant system would certainly 

 change its place when the eye was made to wander over the mirror*. 

 In point of fact, however, that centre does not change place except 

 when the whole head is moved, in which case it does so proportion- 

 ally. 



I ascribe the phaenomenon to a peculiar mode of action in the 

 nervous part of the apparatus of vision proper to it as an elastic 

 tissue, in virtue of which it tends, like the tissues and media expe- 

 rimented on by Chladni, Savart, Faraday, and others, and doubtless 

 all elastic tissues and media, to distribute all motions impressed upon 

 it in symmetrical systems ; a view of the matter having very in- 

 teresting bearings upon the principles of taste, — during the investi- 

 gation of which it was that this experiment first occurred to me, — 

 and one calculated to explain several seemingly unaccountable phae- 

 nomena as to the distribution of sensibility in the retina. 



Johnfield by Dundee, Oct. 14. 



STARCH. 

 M.Payen,in a memoir on starch, considers that this'substance, in 

 whatever manner or from whatever part of vegetables it may be ob- 

 tained, whatever may be its form, its age, or its state of aggregation, 

 has always the same chemical constitution: its conversion into dex- 

 trine by diastase, sulphuric acid, potash, «&c., are modifications of 

 its physical properties, without in the least degree altering its che- 

 mical constitution, which is represented by C2 }\h Qs. — Jour, de 

 Pharmacie, Oct., 1836. 



ON THE ACTION OF SULPHUROUS ACID ON STEEL. 



The experiments which M. Vogel has made on this subject lead 

 to the following results : 



*[ We do not feel certain that this would be the case, if the seat of the 

 symmetrizing power be in the retina. — EpiT.] 



2H3 



