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Platinum spiral

Measurements of the true specific heats at low temperatures have been carried out by Eucken, who worked in such a way that to a weighed quantity of the substance in the form of a block, or in a proper isolated vessel, a known quantity of heat was added by means of an electrically heated platinum spiral, the resistance of wThich at the same time served to measure the temperature. The quotient of the electrical energy spent by the rise of temperature gives the specific heat. The correction for cooling (in vacuum of 5 Jo mm.) amounted to 20 per cent., and for heat capacity of the apparatus 5 per cent., yet the results are stated to be accurate to 1 per cent. [Pg.14]

The counter electrode consists of a platinum spiral placed symmetrically around the working electrode. [Pg.146]

The room was made dark and when a hot glass tube had cooled until it was just barely visible, a fragment of iodine was thrown into the tube, which thereupon filled with luminous vapours. To obtain more brilliancy one heats the vapour of iodine in a Bohemian glass tube by means of an enameller s lamp. The contents of the tube look like a red-hot bar of iron. One may also volatilize iodine around a platinum spiral brought to a vivid incandescence the luminous vapour rises like a real flame about the spiral. It is a case of farm without combustion. The light from the iodine gives a continuous spectrum, or rather a confused primary spectrum one perceives traces of characteristic channellings but no lines of the secondary spectrum. [Pg.61]

Compared with the ICP, other atomic spectrometric detectors are not widely coupled to HPLC. Several interfaces have been described for AAS detector. Methods include a rotating platinum spiral collection system (Ebdon et al., 1987) and a flow injection thermospray sample introduction system (Robinson and Choi, 1987). Post-column hydride generation is also popular with AAS detection as will be described later. Pedersen and Larsen (1997) used an anion-exchange column to separate selenomethionine, selenocysteine, selenite and selenate with both FAAS and ICP-MS. The detection limits for the FAAS system were lmg H1 compared with 1 fig l-1 for ICP-MS. HPLC-MIP systems have been described to an even lesser extent. These either use elaborate interfaces to overcome the problems of quenching the low-power plasma (Zhang and Carnahan, 1989) or use a modified argon/oxygen mixed gas plasma (Kollotzek et al., 1984). [Pg.78]

Cadmium, copper and zinc associated with various proteins have been studied by means of an ion chromatograph coupled to a flame AAS (Ebdon et al., 1987). The design of the interface meant that the nebuliser of the AAS could be eliminated, thus avoiding the low efficiency of the nebulisation. Effluent from the HPLC was collected as discrete aliquots on a series of rotating platinum spirals that entered the flame atomiser. An atom trap (tube in flame) was included to increase the sensitivity of the detector by allowing the analyte to remain for a longer period in the optical path. [Pg.417]

Platinum is not only suitable for accelerating reduction processes, but is also an excellent catalyst when oxidation is effected by air or oxygen. Formaldehyde was first prepared by passing the vapour of methyl alcohol and air over a heated platinum spiral.15... [Pg.100]

Bouveault1 claims that the yield of adipic acid is better on electrolyzing the methyl ester-salt in methyl-alcoholic solution. He obtained a yield of 80% by using a mercury cathode and a hollow platinum spiral anode, through which a current of cold water was passed. The acid succinic methyl ester occurs as the principal by-product, also a neutral methyl ester of a tribasic acid which was not investigated. [Pg.111]

A.F. Hofmann, in 1868, prepd formaldehyde by passing a mixture of methanol vapors and air over a heated platinum spiral, serving as a catalyst. The following reaction takes place CH3OH+ / 02 (air) - CH20+H20. The present method of preparation is essentially the same as used by Hofmann, except that cheaper catalysts than platinum are used, such as Ag and Cu in multilayer gauzes or screens, vanadium and molybdenum oxides, iron oxides or other metal oxides. Limited amounts of formaldehyde are also prepd by the oxidation of natural gas and the lower petroleum hydrocarbons... [Pg.545]

Electrode-Preparation and Aging. Electrode preparation procedures are given by Keston (14) and by Ives and Janz (II). Electrodes were prepared from a paste containing 90% silver oxide and 10% silver bromate placed on a platinum spiral and heated in a furnace for 7 min at 650°C. Janz and Taniguchi (12) have reviewed the preparation, reproducibility, and stability of this electrode. Taylor and Smith (13) found the equilibrium potential to be stable within 0.02 mV. Electrodes... [Pg.355]

If, however, the precipitate of diphenylurea is too small to weigh accurately, it is converted to ammonia and determined colorimetrically by the Nessler method. In this procedure, the filter paper is removed from the funnel and placed in a small beaker 4 ml. pure sulphuric acid (66° Be) are added, allowing this to flow slowly over the platinum spiral and through the funnel so as to wash off all traces of adherent precipitate. To the mixture obtained in this way 10 mgm. mercuric sulphate are added and the whole is then kept near boiling temperature for 2 hours. After allowing to cool, 20 ml. distilled water are added and the mixture is transferred to a 200-ml. flask containing 0-25 gm. sodium thiosulphate dissolved in 100 ml. water to remove the mercury. The beaker is washed with water which is added to the contents of the flask until the total volume is about 150 ml. and the ammonia determined in this. [Pg.83]

The usual diaphragm type of electrolytic cell is used in all of the experiments except those at a boiling temperature. (Experiment No. 10, Table 1.) The coll is immersed in a cooling mixture or cold water to maintain the desired temperature. A mechanical stirrer is used in all experiments. Unless otherwise stated, the mercury layer is not stirred with the mechanical stirrer. In all cases a platinum spiral anode is used. [Pg.41]

When a stream of air is passed over liquid ether and then over a red hot platinum spiral, hydrogen peroxide may be continuously obtained by scrubbing the vapors with water. Ether apparently forms a peroxide under the conditions, which is decomposed by the scrubbing water. If the products are condensed and the liquid product slowly evaporated over sulfuric acid, a crystalline material remains which is slowly volatile and is capable of detonation. It is also capable of liberating iodine from potassium iodide.184 On the other hand, if red hot pumice is substituted for the platinum catalyst, the scrubbing water shows no peroxide formation, and aldehyde and acetone are the chief products.180... [Pg.99]

For the determination of ICE using the oxygen flow rate method, a two compartment cell of 150 ml capacity was used the anode was a cylinder of 35 cm2 surface area and the cathode was a platinum spiral (4 cm2) enclosed in a 10 ml porous porcelain pot stirring was provided by a magnetic bar. [Pg.79]

The phenylhydrazine hydrochloride, or Iree base, (0.2 gram) is mixed with the arsenic acid solution (60 cc), and the liquid boiled steadily by the help of a small platinum spiral in a reflux apparatus for 40 min-... [Pg.128]


See other pages where Platinum spiral is mentioned: [Pg.539]    [Pg.545]    [Pg.167]    [Pg.331]    [Pg.65]    [Pg.53]    [Pg.209]    [Pg.397]    [Pg.192]    [Pg.85]    [Pg.178]    [Pg.76]    [Pg.228]    [Pg.337]    [Pg.244]    [Pg.167]    [Pg.545]    [Pg.159]    [Pg.68]    [Pg.69]    [Pg.70]    [Pg.77]    [Pg.244]    [Pg.88]    [Pg.4981]    [Pg.356]    [Pg.443]    [Pg.368]    [Pg.460]    [Pg.212]    [Pg.266]    [Pg.191]    [Pg.744]    [Pg.16]    [Pg.120]   
See also in sourсe #XX -- [ Pg.80 ]




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