D 



Sii Intelligence and Miscellaneous Articles. 



will fall as chromate and sulphate of lead, with the chromic acid, on 

 dilution with the solution of bichromate. The mixture is then al- 

 lowed to cool, and the chromic acid gradually crystallizes in beau- 

 tiful dark crimson needles. Decant the fluid part, and place the 

 crystals with the adhering sulphuric acid on a thick flat tile of bis- 

 cuit porcelain ; another tile is then to be placed upon the crystals, 

 and the whole submitted to pressure for a considerable time. On 

 removing the chromic acid, it will be found in a perfectly dry state, 

 and yielding a mere trace of sulphuric acid on examination. 



" On the employment of Chromic Acid as an agent in Galvanic 

 arrangements," by Robert Warington, Esq. (See Memoirs, Vol. 

 I., Art. 9.) 



LI. Intelligence and Miscellaneous Articles. 



ON FIBRE. BY DR. MARTIN BARRY. 

 R. BARRY requests us to add the following, in connexion with 

 his Memoir on Fibre, an abstract of which is given at p. 321. 

 The " white substance of the nervous fibre," surrounding Remak's 

 " band-like axis," consists of filaments having the remarkable struc- 

 ture above described, and often curiously interlaced with one an- 

 other, as though each of them had a spiral direction. In examining 

 the substance of the optic, olfactory, and auditory nerves, as well as 

 that of the brain and spinal chord. Dr. Barry employed for the most 

 part such as had been preserved in spirit ; and, besides using ex- 

 tremely minute portions, he very often avoided adding i.iny covering 

 whatever, the weight of thin mica itself being sufficient to rupture 

 or to flatten this delicate substance, and thus entirely prevent its 

 structure from being seen. In the parts last mentioned, he finds red 

 discs, which pass first into rings, and then into spirals. In fasciculi 

 from the spinal chord, and surrounded by spiral filaments, he met 

 with a "band-like axis," which perhaps corresponds to that of Re- 

 mak in the nerves : but if so. Dr. Barry's observations go farther 

 even than Remalv's. The "axis" described by this observer was 

 found by him to be susceptible of division into filaments. So also 

 is the one described by Dr. Barry. But the latter adds, that each 

 filament is a compound object, which enlarges, and, from analogy, 

 may contain the elements of future structures, formed by division 

 and subdivision, to which no limits can be assigned. The sperma- 

 tozoa, mentioned in the abstract, were from the epididymis of a per- 

 son who had died suddenly. The depression noticed in their discoid 

 extremity — corresponding apparently to the " sugient orifice " of 

 some authors — is probably analogous to the source of new substance 

 in other discs. In these examinations. Dr. Barry has generally added 

 to the objects dilute spirit (sp. gr. about 0940), containing about 

 g^yth of corrosive sublimate. Spirals from the leaf- stalk of the 

 strawberry, after the addition of this reagent, were seen to have di- 

 vided into parallel filaments having the same structure as those above 

 described. Flax presented a quadruple coil of such filaments. In 

 early states of voluntary muscle also, tliere w-ere seen double and 

 quadruple coils, evidently produced by the same means — division. 



