scholarly journals Some researches on flame

1833 ◽  
Vol 2 ◽  
pp. 59-61 ◽  
Keyword(s):  
High Temperature ◽  
Glass Tube ◽  
Platinum Wire ◽  
The Wire ◽  
Humphry Davy ◽  
Lower Temperature ◽  
Sulphuretted Hydrogen

This communication is subdivided into four sections, of which the first treats of the effect of rarefactions of the air, by diminished pressure, upon flame, and explosion. An inflamed jet of hydrogen was placed in the receiver of an air-pump, and the flame was observed to enlarge during exhaustion, till the gauge indicated a pressure of one fourth or one fifth; it then diminished in size, but was not extinguished till the pressure was reduced to between one seventh and one eighth. A somewhat larger jet burned until the rarefaction amounted to one tenth, and rendered the glass tube whence the gas issued white hot. To this circumstance the author refers the long-continued combustion of the gas, and thinks the conclusion confirmed by the following experiment. A platinum wire was coiled round the jet tube, so as to reach into and above the flame, and it became white hot during the exhaustion, and continued red hot even when the pressure was only one tenth. The lower part of the flame was now extinguished, but the upper part in the contact of the wire continued to bum till the pressure was reduced to one thirteenth. The flame, therefore, of hydrogen is extinguished in rarefied atmospheres, whenever the heat it produces is insufficient to communicate visible redness to platinum wire. Sir Humphry Davy was thus led to infer, that those combustibles which require least heat for combustion would burn in rarer atmospheres than those requiring more heat; and that bodies which produce much heat in combustion would burn in rarer air than those producing little heat, and experiments are detailed proving this to be the case: thus, an inflamed jet of light carburetted hydrogen, which produces little heat in combustion, and requires a high temperature for its ignition, was extinguished whenever the pressure was below one fourth, even though the tube was furnished with a wire. Carbonic oxide burned under a pressure of one sixth; sulphuretted hydrogen of one seventh. Sulphur, which burns at a lower temperature than any other ordinary combustible, except phosphorus, had its flame maintained in an atmosphere rarefied 15 times, and phosphuretted hydrogen was inflamed when admitted into the best vacuum of an excellent air-pump. The author next proceeds to consider the influence of rarefaction, produced by heat, upon combustion and explosion. A volume of air at 212° is expanded to 2·25 volumes. At a dull red heat its probable temperature then is 1032°, provided it expand equably for equal increments of heat.

scholarly journals I. The Bakerian Lecture. - On certain phenomena of voltaic ignition and the decomposition of water into its constituent gases by heat

1847 ◽  
Vol 137 ◽  
pp. 1-16 ◽  
Keyword(s):  
General Practice ◽  
Nitric Acid ◽  
Glass Tube ◽  
Platinum Wire ◽  
Pure Oxygen ◽  
Philosophical Magazine ◽  
The Wire ◽  
Decomposition Of Water ◽  
At Will

In the Philosophical Magazine for August 1841, I recommended for eudiometrical purposes, the use of a platinum wire ignited by a voltaic battery. In Plate I. fig. 1, is represented a form of apparatus for this purpose; it consists of a tube of Bohe­mian glass, with a loop of platinum wire 1/80th of an inch diameter sealed into its upper end; the size of the glass tube may be adapted to the quantity of gas sought to be analysed, and may when necessary be reduced to extremely small dimensions, one-eighth of an inch being ample; into this the gas may readily be made to ascend, by the insertion of a wire of copper, platinum, or glass, as may be suitable to the gas: two cells of the nitric-acid battery are sufficient fully to ignite the wire, and the same battery supplies, by electrolysis, pure oxygen and hydrogen for the analysis. Since the period when I first proposed this, I have seldom used any other apparatus for such gaseous analyses as are performed by combining the gas to be examined with oxygen or hydrogen. This eudiometer possesses the advantage of enabling the operator either to detonate or slowly to combine the gases, by using different powers of battery, by interposing resisting wires, or by manipulation alone, —a practised hand being able by changing the intervals of contact to combine or detonate the gas at will. My general practice has been to produce a gentle heat in the wire until the gases con­tract, and then gradually to increase the heat until a full ignition takes place, by which means all the objects of the eudiometer of Volta are fulfilled, without detona­tion, without dependence on the fickle electric spark, and without thick tubes, any danger of explosion, or of the gases being projected from the eudiometer. I have commenced with a description of this eudiometer, as it has been indirectly the means of my undertaking the experiments detailed in this lecture; and as its very great convenience has never been generally understood, I think that in strongly re­commending it, I shall be of service to chemists.

scholarly journals XIX.—Magnetization and Resistance of Nickel Wire at High Temperatures. Part II.

1907 ◽  
Vol 45 (3) ◽  
pp. 547-554
Author(s):  
C. G. Knott
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Electrical Resistance ◽  
British Association ◽  
Nickel Wire ◽  
Present Communication ◽  
Association Meeting ◽  
The Subject ◽  
The Wire

The experiments which form the subject of the present communication were carried out two years ago, and supplement results already published. A brief note of some of the results was read before the Society in June 1904, and was also read before the British Association Meeting at Cambridge in August of the same year.The previous paper discussed the effect of high temperature on the relation between electrical resistance and magnetization when the wire was magnetized longitudinally, that is, in the direction in which the resistance was measured.The present results have to do with the effect of high temperature on the relation between resistance and magnetization when the magnetization was transverse to the direction along which the resistance was measured.

Comparison of Two Protein Extraction Methods for Tea Residues

2011 ◽  
Vol 138-139 ◽  
pp. 933-936 ◽  
Author(s):  
Xuan Chen ◽  
Hong Yu Luo ◽  
Jun Yu ◽  
Peng Xiang Yue ◽  
Lin Zhou ◽  
...  
Keyword(s):  
High Temperature ◽  
Protein Extraction ◽  
Ethanol Concentration ◽  
Extraction Methods ◽  
Extraction Yield ◽  
Factorial Experiments ◽  
Extraction Technology ◽  
Digestion Method ◽  
Solid Ratio ◽  
Lower Temperature

Alcohol-alkali method and base digestion method were investigated to extract proteins from tea residues, respectively. According to single factorial experiments, results showed that the optimal extraction technology of alcohol-alkali method were pH 12, temperature of 80 °C, ethanol concentration of 60%, liquid-solid ratio of 40, 60 min, and the protein extraction rate reached 15.0%. And the optimal extract conditions of base digestion were pH 12, temperature of 80 °C, liquid-solid ratio of 50, 80 min, which made the protein yield reached 31.5%. Furthermore, alcohol-alkali method was more beneficial to protein extraction from tea residues under lower temperature and weak alkali condition (40-60 °C, pH 8-10). While base digestion had higher extraction yield under high temperature and strong alkali condition (60-80 °C, pH 11-12).

Mineral partitioning in milk and milk permeates at high temperature

2011 ◽  
Vol 79 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Divina D Kaombe ◽  
Yanhong Du ◽  
Michael J Lewis
Keyword(s):  
High Temperature ◽  
Calcium Phosphate ◽  
Temperature Dependence ◽  
Casein Micelle ◽  
Soluble Phase ◽  
Ionic Calcium ◽  
Separation Temperature ◽  
Two Temperatures ◽  
Lower Temperature ◽  
Mineral Partitioning

The soluble phase of milk was separated at 20 and 80°C using ultrafiltration. The resulting permeates were then subjected to further ultrafiltration and dialysis at close to these two temperatures. It was found that pH, Ca2+ and soluble Ca decreased as the separation temperature increased both in original UF permeates and in dialysates obtained from these permeates, but P decreased only slightly. The major reason for these changes was due to the precipitation of calcium phosphate/citrate complexes onto the casein micelle with concomitant release of H+. The pH of both permeates and dialysates from milk at 20°C were slightly higher than for milk. When UF permeates collected at 20 and 80°C, were each dialysed at both these temperatures, the dialysate collected at 80°C showed much less temperature dependence for pH and ionic calcium compared with that collected at 20°C. This is in contrast to milk, which shows considerable temperature dependence for pH and ionic calcium. Further experiments revealed that the pH and Ca2+ concentration of permeates showed high temperature dependence above the temperature at which they were separated, but a much lower temperature dependence below that temperature. These findings suggest that dialysis and UF of milk at high temperature provide the best means yet for estimating the pH and ionic calcium of milk at that temperature.

Evidence for inhibitor involvement in thermodormancy of Grand Rapids lettuce seeds

1991 ◽  
Vol 1 (4) ◽  
pp. 263-267 ◽  
Author(s):  
J. G. Chris Small ◽  
Yitzchak Gutterman
Keyword(s):  
High Temperature ◽  
Temperature Treatment ◽  
Small Extent ◽  
High Temperature Treatment ◽  
Ultraviolet Region ◽  
Distilled Water ◽  
Osmotic Effect ◽  
Lettuce Seeds ◽  
Grand Rapids ◽  
Lower Temperature

AbstractProlonged imbibition and incubation of lettuce seeds at a supraoptimal temperature induces secondary dormancy. Such seeds no longer germinate when returned to conditions optimal for germination of non-dormant seeds. The possibility that inhibitors are involved in the induction of thermodormancy was investigated.Washing of thermodormant seeds restored germination to a small extent. However, continuous leaching of seeds during high-temperature treatment with distilled water, largely prevented the induction of thermodormancy. Such seeds were qualitatively similar to nondormant seeds, i.e. they required only light to germinate at a lower temperature and germinated in the dark if given GA3. The germination water from thermodormant seeds inhibited the germination of non-dormant lettuce seeds. The inhibition was not an osmotic effect. Absorbance in the ultraviolet region was higher in germination water from thermodormant seeds than that of non-dormant seeds. It is concluded that inhibitors are involved in the induction of thermodormancy of lettuce seeds.

scholarly journals Bakerian Lecture—On certain phenomena of voltaic ignition, and on the decomposition of water into its constituent gases by heat

1851 ◽  
Vol 5 ◽  
pp. 657-659
Keyword(s):  
Carbonic Acid ◽  
Glass Tube ◽  
Platinum Wire ◽  
Philosophical Magazine ◽  
Decomposition Of Water

The author refers to an eudiometer, an account of which was published by him in the ‘Philosophical Magazine’ for 1840, formed of a glass tube, into the closed extremity of which a loop of plati­num wire was sealed. The gases to be analysed were mixed in this tube with a given volume of oxygen and hydrogen, and detonated or slowly combined by the voltaic ignition of the platinum wire. He was thence led to try a further set of experiments on the analysis, by this instrument, of such gases and vapours as are decomposable by heat; the process being capable of much greater exactness than the received one of passing them through ignited tubes. The re­sults of the analyses of several gases by this means are given in the paper. When carbonic acid and hydrogen are mixed in equal volumes and exposed to the ignited wire, the hydrogen abstracts oxygen from the carbonic acid, and leaves carbonic oxide. Con­versely, when carbonic oxide is exposed over water to the ignited wire, it abstracts oxygen from the aqueous vapour, and forms car­bonic acid. It thus appeared, that provided there were bodies present capable of absorbing by affinity the elements of water, ignited platinum would either compose or decompose water. The author was thence led to hope that he might by ignited platinum decompose water into its constituents, without absorption by other bodies, and thus pro­duce converse effects to those already known. In this he ultimately succeeded by various methods, in some of which the ignition was produced by electrical means; in others by ordinary calorific pro­cesses, such as the oxyhydrogen blowpipe, &c.

A Study on Influence of Annealing and Aging on High Temperature Internal Friction in Al-Zr Alloy

2012 ◽  
Vol 535-537 ◽  
pp. 1027-1030
Author(s):  
Xiao Hui Cao ◽  
Yu Wang
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Grain Boundary ◽  
Low Frequency ◽  
Grain Boundary Sliding ◽  
High Temperature Side ◽  
Internal Friction Peak ◽  
Average Grain Size ◽  
Lower Temperature ◽  
Zr Alloy

By using a low frequency inverted torsion pendulum, the high temperature internal friction spectra of Al-0.02wt%Zr and Al-0.1wt%Zr alloys were investigated respectively. In Al-0.02wt%Zr alloy, the conventional grain boundary internal friction peak (Pg) is observed with some small unstable peaks. In Al-0.1wt%Zr alloy, the bamboo peak is observed to appear at the high temperature side of the conventional grain boundary internal friction peak. The conventional grain boundary internal friction peak decreased and moved to higher temperature. The bamboo peak owns an activation energy of 1.75eV. When average grain size exceeded the diameter of samples, Pb strength was reduced and its position was shifted to a lower temperature. Based on the grain boundary sliding model, Pg and Pb peaks were explained. Their dependence on annealing temperature and time was determined by considering the effects of contained Ce atoms and other impurities on the relaxation across grain boundary.

Sign in / Sign up

Export Citation Format

Share Document