Cotton Wick Research Articles

Method For Recording Electrical Activity of the Isolated Heart

The simultaneous recording of electrical activity from two sites on an isolated mammalian heart by a simple and effective method is described. The use of agarfilled polyethylene tubing containing cotton wick electrodes offers distinct advantages compared to the usual platinum hook electrodes.

The evaluation of ventilation.

The problem of describing quantitatively the effective ventilation in a room when the air within the room is imperfectly mixed is discussed. It is suggested that the protection afforded by the ventilation to any given position against airborne contamination liberated at any other position can be best expressed in terms of the integrated exposure at the first point following liberation of a tracer substance at the second. This quantity is called thetransfer indexand its reciprocal theequivalent ventilationapproaches numerically to the rate of supply of ventilating air as the mixing of air within the room approaches completeness. Nitrous oxide is a convenient tracer gas for making such measurements.A method is also described whereby estimates of thetransfer indexcan be made employing only such apparatus as is easily available in a reasonably well-equipped laboratory. This method employs acetone vapour as a tracer substance. The concentration of this vapour in the air is measured by the pH change produced in a dilute solution of hydroxylamine hydrochloride as it flows down a cotton wick exposed to the atmosphere.

INFLUENCE OF ESTRONE ON THE ELECTRIC CHARACTERISTICS AND THE MOTILITY OF UTERINE MUSCLE

THE CHARACTER of the movements of the uterus, in situ and isolated, differs strikingly in different phases of the sexual cycle, suggesting some hormonal influence on essential properties of uterine muscle. In the present paper the effect of estrone on this type of muscle will be investigated and it will be shown that changes in motility can be explained as the result of changes in muscular excitability. Uterine strips from the cat were prepared and mounted as described previously (1). The zinc-zinc sulfate electrodes used for these measurements made contact with the tissue by cotton wicks which were placed on the muscle at a distance of 3 cm. from each other. The potential change produced by treating the region around one of the leads with a 1% solution of KCl was taken to represent the resting potential.

Our Electrical Column

IF a platinum plate be immersed in a porcelain or glass vessel containing dilute sulphuric acid, and another similar plate be immersed in another vessel containing caustic potash solution, then if the two vessels be connected by a siphon tube or a cotton wick, a current will be set up, but which rapidly diminishes owing to the polarization of the metal plates by the deposition of oxygen and hydrogen upon them. Becquerel removed the hydrogen by using nitric instead of sulphuric acid, and increased the current considerably. Dr. Alder Wright and Mr. C. Thomson (Royal Society, February 2, 1888) have been examining this form of battery, and have found many other acids which act in the same way, such as potassium permanganate, potassium bichromate, potassium ferricyanide, and bromine dissolved in sulphuric acid, ferric chloride, hydrochloric acid and chlorine. Moreover, they have removed the oxygen by using a concentrated solution of sodium hyposulphite made strongly alkaline with caustic soda, strong caustic soda with pyrogallol, cuprous chloride, ferrous sulphate, and ammonium chloride dissolved in ammonia. They also found the quantity of oxygen and hydrogen evolved exactly proportional to the current passing. If a silver voltameter were included in the circuit, for every milligramme-equivalent (108 milligrammes) of silver de posited, 1 milligramme-equivalent of hydrogen occupying 11.2 cubic centimetres and 8 milligrammes of oxygen occupying 5.6 cubic centimetres at 0° C. and 760 millimetres, were liberated.