scholarly journals III. On the atomic weight of manganese

1883 ◽  
Vol 35 (224-226) ◽  
pp. 44-48
Keyword(s):  
Carbon Dioxide ◽  
Silver Chloride ◽  
Atomic Weight ◽  
Special Method ◽  
Its Analysis ◽  
A Current ◽  
Sulphuretted Hydrogen

Our attention has been directed for some time to a new determination of the atomic weight of manganese. This communication gives a succinct account of the results of the preliminary stages of such an inquiry, and although the further progress of the investigation may reveal some errors, still we feel convinced the final numbers can in no way differ materially from the present values, and therefore further delay in publication is unnecessary. The atomic weight of manganese has been determined by many chemists, but the resulting values vary considerably according to the special method selected. The results of the different investigators may be divided into two classes—those giving approximately 55 as the number, and those making it about 54. To the former class belong Turner, Berzelius, and Dumas, all of whom use the same method, viz., the determination of the silver chloride yielded by a weighed amount of chloride of manganese. Turner also made determinations from the analysis of the carbonate, and from the conversion of the monoxide into sulphate. Von Hauer used the same method as that employed by him in the determination of the atomic weight of cadmium, viz., the reduction of manganous sulphate to sulphide by ignition in a current of sulphuretted hydrogen. It is probable that this method is not very trustworthy, as, according to Schneider, the sulphide may be contaminated by oxysulphide. Schneider and Rawack belong to the second class of observers, the former employing the oxalate, and from its analysis calculating the atomic weight by deducting the weight of water and carbon dioxide obtained. Rawack, whose experiments were conducted in Schneider’s laboratory, weighed the water obtained by reducing manganoso-manganic oxide to manganous oxide.

scholarly journals On a new method for the determination of atmospheric carbon dioxide, based on the rate of its absorption by a free surface of a solution of caustic alkali

1905 ◽  
Vol 76 (507) ◽  
pp. 112-117 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Free Surface ◽  
Partial Pressure ◽  
Atmospheric Carbon Dioxide ◽  
Liquid Surface ◽  
Caustic Alkali ◽  
Optimal Velocity ◽  
Rate Of Absorption ◽  
A Current

In an appendix to a paper on the static diffusion of gases, communicated to the Society in 1900, it was shown that when a current of air containing a constant proportion of carbon dioxide is caused to move in a turbulent stream over the free surface of a solution of caustic alkali, the rate of absorption of that gas increases with the velocity of the air-current up to a certain optimal speed, beyond which no further increase in the speed of the current influences the rate of absorption. It was further shown that when the optimal velocity of the air-current has been reached, and the temperature is maintained practically constant, the rate of absorption then varies directly as the partial pressure of the carbon dioxide in the air. In other words, if under the above conditions the rate of absorption per unit of area of the liquid surface is a for a partial pressure of carbon dioxide represented by and is for a partial pressure of p' , then at similar temperatures, a / p = a' / p' . A suggestion was also made that this principle might be found applicable to a determination of the carbon dioxide in air, and that if the method were found to be a practical one it would have the manifest advantage of not requiring any measurement of the air from which the gas was absorbed.

THE DENSITY OF CARBON DIOXIDE

1930 ◽  
Vol 2 (6) ◽  
pp. 388-395 ◽  
Author(s):  
D. LeB. Cooper ◽  
O. Maass
Keyword(s):  
Carbon Dioxide ◽  
Molecular Weight ◽  
Pressure Range ◽  
Atomic Weight ◽  
Mean Value ◽  
Two Temperatures ◽  
The Mean

Modifications are described by the Maass and Russel method for the determination of the densitites of gases which permit an accuracy of about one part in 10,000. The determination has been made of the density of carbon dioxide at two temperatures and over a pressure range of 75 to 25 cm. of mercury. The mean value obtained for the molecular weight of carbon dioxide at zero pressure is 44.0033 ± 0.002, from which the atomic weight of carbon is found to be 12.0033 ± 0.002.

An investigation of the chemical changes taking place in the mixed lime sulphur-lead arsenate spray

1925 ◽  
Vol 15 (3) ◽  
pp. 307-326 ◽  
Author(s):  
WM. Goodwin ◽  
H. Martin
Keyword(s):  
Carbon Dioxide ◽  
Chemical Properties ◽  
Oxidation Products ◽  
Chemical Changes ◽  
Lead Arsenate ◽  
Lime Sulphur ◽  
Main Decomposition ◽  
Hydrolysis Of ◽  
Sulphuretted Hydrogen

1. The reaction between lime sulphur and acid lead arsenate is shown to be small and to have little effect on the chemical properties of either material as a spray.2. It is shown that the oxidation of lime sulphur proceeds according to the empirical formula:CaS.Sx + 30 = CaS2O3 + Sx-1and that the calcium sulphides are hydrolysed in aqueous solution.3. The addition of lead arsenate has no effect on the amount of sulphur precipitated from the lime sulphur by oxidation or by the action of carbondioxide.4. Lead arsenate is only slightly decomposed by lime sulphur or by the oxidation products of lime sulphur, the main decomposition being due to the action of sulphuretted hydrogen formed by the hydrolysis of the calcium sulphides. This decomposition becomes marked in the presence of carbon dioxide which reacts on the calcium sulphide to form sulphuretted hydrogen.5. The fungicidal value of the mixed spray—as judged by the mildew killing properties of the polysulphides—is not less than that of lime sulphur alone. Additional fungicidal properties may be expected from the presence in the spray of soluble arsenates and thioarsenates.6. Judging by the chemical changes which take place in the mixed spray the insecticidal value of the lead arsenate would not appear to be greatly affected by the addition of lime sulphur.7. There is an increased amount of soluble arsenic formed by the action of carbon dioxide on the mixed spray which may prove sufficient in amount to cause spray injury.8. The A.O.A.C. method for the determination of sulphate sulphur in lime sulphur solutions is shown to be inaccurate. A method yielding more concordant results is proposed.

scholarly journals XI. The mobilities of the ions produced by Röntegen rays in gases and vapours

1909 ◽  
Vol 209 (441-458) ◽  
pp. 249-279 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Electric Field ◽  
Diffusion Coefficients ◽  
Negative Ions ◽  
Experimental Methods ◽  
Ionic Mobilities ◽  
Monovalent Ion ◽  
The Difference ◽  
A Current

For various reasons the determination of the velocities in an electric field of the ions produced in gases by the action of Röntgen rays is of fundamental importance in electrical theory. A knowledge of the ionic mobilities the velocities under unit electric intensity) affords information with regard to the structure of the ion; if, in addition, the diffusion coefficients of the ions in various gases are known, the charge associated with the ion can be compared with that carried by the monovalent ion in the electrolysis of solutions. Experimental methods of determining the mobilities of the positive and negative ions were devised not long after the ionising action of the Röntgen rays was known. Rutherford determined the values of the sum of the positive and negative mobilities in a series of gases. Zeleny, by comparing the velocity acquired by the ions in an electric field with that of a gaseous current parallel to the field, succeeded in deducing the values of the difference of the ionic mobilities and also their ratio. In later experiments Zeleny employed a current of gas in a direction perpendicular to the electric field and deduced the absolute values of the mobilities in air, oxygen, carbon dioxide, and hydrogen.

scholarly journals V. The atomic weight of chlorine: An attempt to determine the equivalent of chlorine by direct burning with hydrogen

1906 ◽  
Vol 205 (387-401) ◽  
pp. 169-200 ◽  
Keyword(s):  
Potassium Chloride ◽  
Constant Error ◽  
Silver Chloride ◽  
Atomic Weight ◽  
Probable Error ◽  
Reasonable Accuracy ◽  
New Research ◽  
Individual Series ◽  
Long Chain

Some apology seems needed in presenting a new research on the atomic weight of an element already measured with a precision which the highest living critic has emphasised as “the magnificent accuracy of Stas’ determination." Moreover, the present experiments cannot claim an accuracy to be compared with any individual series of Stas’ ratios. But, on the other hand, Stas’ atomic weight of chlorine is derived indirectly from oxygen by a series of operations which include the determination of (1) the oxygen in potassium chlorate, (2) the silver equivalent to the molecule of potassium chloride, and (3) the composition of silver chloride. Stas himself has assigned different values to these ratios at different times; e. g ., in 1860 he found that 100 parts of silver were equal to 69·103 of potassium chloride, in 1882 he found 100 of silver equal to 69·119, and in his latest work to 69·123 of potassium chloride. Therefore, although Stas’ value 35·457 (O = 16) is in satisfactory agreement with Clarke’s value 35·447 re-calculated from all the best determinations, it is possible that some constant error may occur in some part of the long chain connecting the value of hydrogen with that of chlorine, an error which would be repeated from link to link., and would become evident only when the two ends of the chain were connected up. A direct comparison between hydrogen and chlorine might not only serve to detect any systematic error in this chain of ratios, but such a comparison, inasmuch as it does not involve the probable error of other ratios, would be cœteris paribus more exact. Again, the closing of the chain between hydrogen and chlorine with reasonable accuracy would permit the accidental errors to be distributed and prevent their accumulation at the unconnected end. The accumulated “probable error” in Clarke’s recalculated value for chlorine is ±·0048; the “probable error” of our nine experiments is ±·0019.

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