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[[circled]] 128 [[circled]] Dec 24th 1844 | Exp. on molecular action Mr Eckfelt of the mint has made a series of experiments on the specific gravity of metals, as changed by hammering and heating. Mr Magand of Philadelphia thinks that no pure metal can be hammer hardened. I have seen it stated somewheres that heat is given out in the striking of discs during the first stroke, but not the second. Ask if the specific gravity is increased by the process of coining. Mr. Cornelius showed me the operation of a new polishing powder he had discovered, it is nothing more than Henrys calcined magnesia. It gives a remarkable fine polish to steel. It is applied by rubbing on a surface of canton flannel. It possesses one advantage insofar to the galvanic process of guilding, it can be removed from the surface by a strong solution of sugar which, according to the statement of Mr. C., disolves the magnesia, and in this way removes it from the surface, other substances adhere and cannot be entirely removed. Mr. C proposes to make a reflector for a telescope by means of the galvanic process and then cover it with a coating of silver polished by this means. (For an exp on Molecular action, see p. 69) [Dr. Ellet informed me that when the water was passing off the front side of a Daguerreotype plate, which had been set on edge to drain, small nodes was seen moving up the inner surface of water.] For Savart's paper on the sheet formed by water impinging on a disc, see Annales de Chemie 54, p 123 - 1838. He finds that at the maximum density of water, the diameter of the conical sheet is the [[strikeout]] greatest point [[/strikeout]] [Make experiments on the adhesion of plates at the point of maximum density]. Repeat the exp of savart with soap water. *The viscosity of the water is the [[strikeout]] least [[/strikeout]] greatest at the maximum density. [[end page]] [[start page]] Jany 3rd 1845 } Hole in card Holes in pierced card [[circled]] 129 [[circled]] Purchased five large clock shades from Mr. Pike in New York, which had been covered with tin foil for the purpose of forming a large electrical battery. After considerable trouble in getting them to Princeton and in fitting them into a box, I was much disappointed to day in finding that I could not give them a charge, or at most but a very feeble one. The glass is quite thick, but I do not think this is the difficulty. Repeated to day an experiment previously made in reference to the number of holes in a pierced piece of paper, found as before that when the paper was placed obliquely between the points thus [image] it was pierced with several small holes and one larger, but when the paper was placed directly at right angles to the line joining the points, but one large hole was made. [[in margin]] see page 81 [[/end margin note]] To determine if the same effect would take place in a vacuum, the shock was sent through the paper which had previously been placed under the receiver of an air pump. The number of holes was now greater than when the discharge had been made in the open air. From this experiment, it appears that the air causes the discharge to scatter less. This must be repeated. Also made an experiment on the phosphoresence of the salt called sulphate of potassa placed in a vacuum between two needle points. The salt glowed [[strikeout]] big [[/strikeout]] in this case as if it had been subjected to a weaker shock in the open air.