Arkansas true Democrat., 1858-08-25
To M. D.'s and Scientific Men.

We clip the following items from our ex- changes for the benefit of medical men,
 Those who have no taste for scientific disser- tations will please notice and skip them:
 An instrument called the opthalmoscope by the aid of which the human eye may be inter- nally examined, has recently been brought to the notice of the scientific world. The in- strument is in the form of a concave mirror with hole in the centre, in which lens is inserted; to this another lens is added, which, however, IS separate and moveable. When the instrument is used, a lighted candle is placed by the side of the patient. The concave mir TOT IS then held in front of the eye to be ex- amined, while the movable leans is suspended between the light and the mirror in such a manner as to concentrate the rays of the first on the second. The reflected rays converge on the retina, and on passing through it diverges and renders luminous the whole interior of the eye, which the observer can see by looking through the lens placed in the mirrors centre The reina and the lens form a microscope, the multiply power of which is about five hun dred.
 Advantage is being taken of the solvent and preservative properties of gycerine, in the pre- paration of medicines, both for internal and ex- ternal use. The article is believed to approach very nearly to diluted alcohol in its solvent power. It ltissupposed to possess thesame power of supporting nutrition as cod-hver oil, and to be more easily digested in many cases; this however, requires the confirmation of expe- rience. Many specimens have been exhibited, of medicines prepared with it, such as ioide /. of iron, quinia iodde of quiuia, carbonate of iron, iodine tannin, perphosphate of iron, etc; and it is extremely probable that in many cases gycerine will supersede alcohol as solvent and preservative. A medical writer also rec ommends glYcerine as an invaluable remedy for insect bites.
 At meeting of the English Royal Society during the past year, NJ. Brown Sequard pre- scented a communication on the action of light on muscular flores, independent of the influence of the nerves. That light is capable of produc- ing such an effect was mentioned by several of the old anatonists, but later authorities repudi- ated the idea, and the subject remained unno- ticed. The experiments, however, of NJ. Se- guard prove that some portions of muscular tibre-the iris of the eye for example-are af- tected by light, independently of any reflex ac- ton of the nerves, thereby confirming former experiences. The effect IS produced by the it. luminating rays only-the chemical and heat rays remaining neutral So far as is yet known, this muscle Is the only one on which the light thus takes effect and henceforth the statement that muscular fibre may be stimulated without the intervention of nerves will have to be re- ceived as truth.
 "Respiration the cause of circulation" is the title of theory recently proposed by Mrs. En- ma Willard the well known authoress. to &C., count for the circulation of the blood, in oppo- siton to the theory of Harvey, which main- talns that the impusive stroke of the hearts beat is the sole motive power. According to the views of Mrs. w., the cause of the circula- ton is to be found in respiration, that function bringing into the lungs, on the one hand, carbon mingled in the venous blood, as the fuel of the animal fre,-and on the other oxygen, derived from the atmosphere, to consume it; these be- ing in the lungs separated by membrane, per- meable by gases, though not by undecomposed fluid or air. Thus the carbon and the oxygen intermingling in the lungs animal combustion ensues, and heat evolved; this passes into the blood, which is about seven eighths water.-- The lungs being in partial vacuo, and having temperature at least thrty-fve degrees above that required in complete vacuum to change water into vapor, portion of the water con- talned Tn the blood becomes steam. The VOL ume of the blood thus enlarged exerts a speci- fc force. The valves on the right side of the heart close against 1t, while those on the left open, to give it free passage.
 Professor Smith, of the Pennsylvania Medical College, who lately had the opportunity of ex- amining and experimenting upon St. Martin, the Canadian, who has fstulous orifce in his stomach, has arrived at the following general conclusions: That the secretions of the sto- mach, when digesting are invariably acid; that the acid reaction was not due to the presence of phosphoric acid; that if hydrochloric acid was present, it was in very small quantities; and hate ] 4l,. teristc reaction was tactic acid. In every in- stance, and with all the kinds of food employ ed, the reaction of the fluid of digestion was distinctly acid to litmus paper, while that of the empty stomach-as shown by the introduction of test papers through the fistulous orifice, and of the fluid obtained by mechanical irritation was as distinctly neutral