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24 March 23rd 1843 Made an experiment today on the "pasivity" of iron. A piece of iron wire was heated, and then suffered to cool. On plunging this into strong nitric acid, no action was perceptible, and this state is called pasivity. The idea had occurred to me that perhaps if the wire were magnetized and demagnetized while in the acid, the natural state would return. On making the experiment however, the effect was not produced. The iron remained in the acid unaffected. The experiment consisted in surrounding the glass tube containing the acid, and into which the wire was dipped with a coil. When the passive wire was made, the negative element of a galvanic [[encircled]]couplet [[encircled]], the passive state was destroyed, and action produced. [[end page]] [[start page]] April 24th 1843 25 Being in Phild, I was requested, or I should say invited, to call and see a new microscope, lately imported by Dr. Beck(son of P. Beck Esq.) from England, this is the most perfect instrument of the kind which has yet reached this country. It is furnished with all the arrangements for ease of use as well as for exhibiting everything at present known, in reference to the microscope. With this instrument, I made two original observations, or at least two which I do not know to have been previously made. The first was in reference to starch. This substance is contained in minute [[membraneacious?]] bags which, when wet, swell and burst; the starch has therefore been considered a kind of organic substance. Each particle under the microscope presented an appearance similar to the nodules of indurated clay found about Albany [[image-drawing]] of the appearance of the figure. The idea occurred to me to view this by means of polarized light, the effect was beautiful, each particle of starch showed the action called depolarization of light and exhibited the black cross similar to that shown by a crystal of carbonate of lime when viewed parallel to the optical axis. This fact proves that the starch within the bags is in a state of segregation approximating crystalization. The black cross was not perfect, but the arms were curved somewhat irregularly the centre of the cross in each case was the same as that of the concentric circles which were observed on the surface of the particle without the aid of polarized light. [See the figure] The other observation with this microscope was in reference to capillarity. According to the theory of Poisson, the fluid which comes in contact with the plate of glass suffers a change of density. The idea occurred to me sometime ago, that if this were true to any appreciable degree, it might be rendered evident by means of the transmission of polarized light. The effect was as I anticipated. When a small quantity of water was placed between two glass plates, separated by a frame of thin writing paper, and this submitted to the action of polarized light
Transcription Notes:
09-28-14-BW "membraneacious" = misspelling of "membranaceus" http://en.wiktionary.org/wiki/membranaceus