THE ANALYST. 145 APPARATUS, ETC. A Modification of the Calorimetric Bomb. E. Rengade. (BiiZZ SOC. Chz'??~., 1908 [iv.], 3, 188-190.)-The modification of Mahler's calorimetric boinb shown in the figure was designed for determinations in which the reaction is made to take place in a liquid medium. For the study of the action of water on alkali metals and similar reactions the electric- sparking wires are dispensed with, a movable steel rod termin- ating in a flat disc, d, being used for breaking the glass vessel, a, which contains the substance, and is attached by means of fine wire to a steel support at the bottom of the bomb. The latter has a capacity of about 220 c.c., and is filled with water, with the exception of a space of about 40 c.c., where the gaseous products of the reaction may lodge, B vacuum being produced by attaching a pump to the tube, r , which is opened by turning.The bomb is suspended in the calorimeter by meaus of a cord attached to the wooden rod, t, which is fixed to the end of the crushing rod, whilst a glass rod, b, is placed inside at an anglo of 4 5 O , so that when a rapid rotatory move. ment is applied, first to the right and then to the left, the liquid within the bomb is thoroughly agitated. The tempera- ture reaches its maximum in four to six minutes after the beginning of the reaction. The gases niay subsequently be withdrawn through the tube, T , measured and analysed, a correction being made for the amount dissolved by the liquid. Super- saturation is prevented by vigorous shaking at the end of the reaction, and a correction is usually necessary for the heat of solution of the gas.The calorimetric values146 THE ANALYST. found may be brought to constant pressure by deducting from them the amount of heat that the gases would absorb if liberated under atmospheric preesure. C. A. M. Rapid Estimation of Carbon and Hydrogen in Organic Substances. P. Breteau and H. Leroux. (Bzdl. SOC. Chim., 1908 [iv.], 3, 15-22.)--The apparatiis here shown embodies the different improvements which have been suggested in the electrical method of combustion (ANALYST, 1907, 32, 238). I t consists of a tube, XN, of porcelain or fused quartz, 13 cm. in length and 6 mm. in external diameter, round which is wrapped platinum wire (containing 20 per cent. of iridium), 0.3 mm.in diameter and 30 cm. in length. The first spiral is connected at I wit11 a platinum wire fused into the tube, whilst the other end is attached to the platinuin wire, OP, passing through the rubber cork, C. The porcelain tube, through which no current of gas is intended to pass, is fixed to a tube, DE, of nickel or (preferably) silver, 4.5 em, long and 0.6 mm. in diameter, the other end of which passes through the rubber cork, C, which fits into's combustion tube, XB, of Jena glass, 35 cm. long and 16 mm. in internal diameter. The substance under examination is placed in the porcelain boat, ,,,,,,, ,,,,,, ,,, ,,,,,,, %. ,,, ,, .,,,", ,,, ,,, I I ,I I - .- %, and introduced into the combustion tube by means of the tube, Its, devised by I>ennstedt for the introduction of a double current of dry oxygen through the semi- capillary tube, SV, and the branch, V. The body of this tube is 12 cm.long and 14 mm. in diameter, and its capillary portion, which is 25 cm. long and 6 mm. in external diameter, passes through the rubber cork, 13, closing the other end or' the cornbustion tube. The inner current of oxygen is passed through the apparatus a t the rate of about a bubble in two seconds, whilst the outer current is regulated to give a considerable excess of gas (about 1 C.C. per second). The platinum spiral is brought to a dull red heat by means of the electric current, and the tube beneath the substance is gently heated at intervals by means of a Bunsen burner so as to briDg about intermittent volatilisation or decomposition.In the case of very volatile sub- stances, such a6 ether, the semi-capillary tube is replaced by a closed tube, and only the exterior current of oxygen admitted. External heating is also dispensed with, the heat of the glowing platinum being sufficient to effect the slow volatilisation of the liquid. The duration of a combustion ranges from fifteen to forty minutes for a, quantity of 0.15 gram, according to the nature of the substance, the end being shown by the disappearance of all residual carbon. Experimental results quoted show that the method is extremely accurate. C. A. M.THE ANALYST. 147 New Form of Colorirneter. G. Steiger. (Jouriz. Jwzer. Chem. SOC., 1908, 30, 215-219.)-1n this instrument the ratio of the thickness of the liquids looked through is measured.The colorirneter consists essentially of a box made with two parallel grooves in its base, in which two graduated glass solution-cells can be moved to and fro, the observer looking through one end of the cells. A hole in the under side of the box allows of the admission of light reflected from a mirror below. Into each cell a glass tube is lowered, carrying at its base a small mirror fixed at an angle of 4 5 O . The lower edges of the mirrors touch the bottoms of the cells when in use. The light coming up through the bottom of the cell, and that reflected through the end of it, will go through the same thickness of liquid, and this distance-the distance to be measured-is represented by the length from the end of the cell to a point obtained by producing the line formed by the angle of the small mirror attached to the glass tube, to the base of the cell. A small correction is necessary, owing to the fact that the light must traverse the glass of the mirror before striking the reflecting surface, and the same on leaving. The distance to be thus deducted is represented by twice the hypotenuse of an isosceles right-angled triangle, the equal sides being those of the thickness of the mirror glass. The strengths of the solutions being then inversely proportional to the thickness of the liquid looked through, if R = the reading of the cell containing the standard with concentration C, and T = the reading of the A. R. T. RC unknown solution with concentration c, tben c = ----.