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Influence of soluble sulphates on Kaolins and clays
CURRENT TOPICS.
437
yet attained its crystalline state of ferrite. On re-hesting a quenched steel, the first effect is to change the iron to the uncrystallized a-form (troostite) from which the carbon (since it is irisoluble in a-iron) is deposited iti sitzt as (Fe&),. This is unable to polymerize into (Fe,C), ( cementite) and remains in suspension; hence it is concluded that troostite contains carbon in suspension and no,t in solution. Above 450’ C. the a-iron crystallizes as ferrite in low carbon steels, and with increasing polymerization of the carbon compound, the remainin g complex mass becomes sorbitic and finally pearlite. W. P. JORISSEN AND H. W. WONDSTRA. (Zeit. Ch.mm. Ind. Kolloide, viii, %)-On exposing a ferric oxide solution prepared by digesting ferric oxide with ferric chloride solution and subsequent dialysis, to the radiation from radium bromide contained in thin glass tubes, the authors were able to confirm the statement of Henri and Mayer, that the ferric oxide solution in presence of a quantity of sodium nitrate insufficient alone to cause coagulation, is coagulated when exposed to the radium preparatioa. Although the ferric oxide solution alone apparently remains unaffected by exposure t-p the radium bromide, it is in fact rendered more sensitive, for generally it is coagulated by quantities of electrolytes msufficient to cause coagulation *of a similar solution which has not been so exposed. The radium rays have no observable similar effect on a silver solution. Action
of Radium
Rays on Colloids.
P. ROHLAND. Cause of Efflorescences on Mortars and Stones. (Z. Chem. Ind. Kol., viii, 48.)-Efflorescences on mortars, bricks, etc., are caused by crystalloid substances (acids, bases or salts) and not by colloids. The extent of the efflorescence depends partly on the porosity of the mortar, bricks, etc., for in a very porous material the soluble salts may crystallize partly in the interior of the material, whereas with a material of close structure the water, with its dissolved salts, is forced to the surface. Soluble salts may separate quantitatively on the surface of mortar, etc., after hardenir;g. For example, if plaster of Paris be guaged with water containing 0.05 Gm. of copper sulphate in solution, the plaster remains pure white during setting and hardening, but after several ‘hours, the blue copper sulphate crystallizes out on the surface quantitatively. Influence
of Soluble Sulphates on Kaolins and Clays. R. xliii, 709, etc.)-The soda-slip casting process has now attained s’uch recognition that the rival theories of plasticity,-ane attributing it to the presence of colloids, the other to soluble salts in the clay,-become of commercial impoftance. The influence of soluble sulphates on the fluidity of slip, and their adsorption by clay, have therefore been examined, and the following RIEKE.
(Sprechmzl,
CURRENTTOPICS.
438
conclusions
,reached.
Most soluble sulphates increase the viscosity barium hydroxide should be added to the slip. The most harmful sulphates are those of calcium, aluminum and the heavy metals. Alkali sulphates stiffen the slip up to 0.1 per cent., then render it more fluid up to 1.0 per cent., and then stiffen it again. Zinc and copper sulphates act in the same way. The curve representing the activity of the salts rises rapidly on small additions of sulphates, but slower on large additions, It is also dependant to some extent on the proportion of cIay to water in the slip. Watery free from sulphates should be used. Clays absorb sulphates in small quantities, though sometimes the clay absorbs the metallic iron, leaving the sulphate iron to withdraw an alkali metal from the clay, by double decomposition. of a slip, and therefore
Electric
Furnaces in Non-Ferrous Metallurgy. J_ W. RICHChem. Elzg., viii, 233.)-The advantages of electricover blast-furnaces are: They produce purer metal castings and crucible quality alloys, due to the absence of injurious gases. They are efficient for roasting sulphide and arsenide ores, as there is The process of concentrating ores no interference with oxidation. They are especially valuable for to mats can be better regulated. reducing to metal, as there will be less volatilization and fume loss, owing to the smaller volume of co,mbustion gases; moreover a uniform temperature can be maintained throughout and only as For roasting ores so as to condense high as may be necessary. the metallic vapors, zinc for example, heat may be supplied inside the retorts instead of outside, thus increasing the calorific efficiency. ARDS.
The
(Met.
Constituents
Active Deposit of Actinium. L. cli, 57. )-Experiments conducted to prove or disprove the existence of a substance giving rise to Act B. and emitting a rays, did not give irrefutable proo,f, but : (I) The assumption that this substance exists furnishes a simple explanation of the peculiar form of Bragg’s ionization curve for the (2) The assumption accounts for induced activity of Actinium. the difference in the law of disappearance of the scintillations for polonium as compared with that of the active deposit of actinium. (3) The initial drop in the decay curve supports the above hypothesis. (4) The hypothesis explains the observation of Geiger and Marsden that IO per cent. of the scintillations produced by the active deposit of actinium are double.
BLANQUIES.
(Comptes
of the
rendtis,
437
yet attained its crystalline state of ferrite. On re-hesting a quenched steel, the first effect is to change the iron to the uncrystallized a-form (troostite) from which the carbon (since it is irisoluble in a-iron) is deposited iti sitzt as (Fe&),. This is unable to polymerize into (Fe,C), ( cementite) and remains in suspension; hence it is concluded that troostite contains carbon in suspension and no,t in solution. Above 450’ C. the a-iron crystallizes as ferrite in low carbon steels, and with increasing polymerization of the carbon compound, the remainin g complex mass becomes sorbitic and finally pearlite. W. P. JORISSEN AND H. W. WONDSTRA. (Zeit. Ch.mm. Ind. Kolloide, viii, %)-On exposing a ferric oxide solution prepared by digesting ferric oxide with ferric chloride solution and subsequent dialysis, to the radiation from radium bromide contained in thin glass tubes, the authors were able to confirm the statement of Henri and Mayer, that the ferric oxide solution in presence of a quantity of sodium nitrate insufficient alone to cause coagulation, is coagulated when exposed to the radium preparatioa. Although the ferric oxide solution alone apparently remains unaffected by exposure t-p the radium bromide, it is in fact rendered more sensitive, for generally it is coagulated by quantities of electrolytes msufficient to cause coagulation *of a similar solution which has not been so exposed. The radium rays have no observable similar effect on a silver solution. Action
of Radium
Rays on Colloids.
P. ROHLAND. Cause of Efflorescences on Mortars and Stones. (Z. Chem. Ind. Kol., viii, 48.)-Efflorescences on mortars, bricks, etc., are caused by crystalloid substances (acids, bases or salts) and not by colloids. The extent of the efflorescence depends partly on the porosity of the mortar, bricks, etc., for in a very porous material the soluble salts may crystallize partly in the interior of the material, whereas with a material of close structure the water, with its dissolved salts, is forced to the surface. Soluble salts may separate quantitatively on the surface of mortar, etc., after hardenir;g. For example, if plaster of Paris be guaged with water containing 0.05 Gm. of copper sulphate in solution, the plaster remains pure white during setting and hardening, but after several ‘hours, the blue copper sulphate crystallizes out on the surface quantitatively. Influence
of Soluble Sulphates on Kaolins and Clays. R. xliii, 709, etc.)-The soda-slip casting process has now attained s’uch recognition that the rival theories of plasticity,-ane attributing it to the presence of colloids, the other to soluble salts in the clay,-become of commercial impoftance. The influence of soluble sulphates on the fluidity of slip, and their adsorption by clay, have therefore been examined, and the following RIEKE.
(Sprechmzl,
CURRENTTOPICS.
438
conclusions
,reached.
Most soluble sulphates increase the viscosity barium hydroxide should be added to the slip. The most harmful sulphates are those of calcium, aluminum and the heavy metals. Alkali sulphates stiffen the slip up to 0.1 per cent., then render it more fluid up to 1.0 per cent., and then stiffen it again. Zinc and copper sulphates act in the same way. The curve representing the activity of the salts rises rapidly on small additions of sulphates, but slower on large additions, It is also dependant to some extent on the proportion of cIay to water in the slip. Watery free from sulphates should be used. Clays absorb sulphates in small quantities, though sometimes the clay absorbs the metallic iron, leaving the sulphate iron to withdraw an alkali metal from the clay, by double decomposition. of a slip, and therefore
Electric
Furnaces in Non-Ferrous Metallurgy. J_ W. RICHChem. Elzg., viii, 233.)-The advantages of electricover blast-furnaces are: They produce purer metal castings and crucible quality alloys, due to the absence of injurious gases. They are efficient for roasting sulphide and arsenide ores, as there is The process of concentrating ores no interference with oxidation. They are especially valuable for to mats can be better regulated. reducing to metal, as there will be less volatilization and fume loss, owing to the smaller volume of co,mbustion gases; moreover a uniform temperature can be maintained throughout and only as For roasting ores so as to condense high as may be necessary. the metallic vapors, zinc for example, heat may be supplied inside the retorts instead of outside, thus increasing the calorific efficiency. ARDS.
The
(Met.
Constituents
Active Deposit of Actinium. L. cli, 57. )-Experiments conducted to prove or disprove the existence of a substance giving rise to Act B. and emitting a rays, did not give irrefutable proo,f, but : (I) The assumption that this substance exists furnishes a simple explanation of the peculiar form of Bragg’s ionization curve for the (2) The assumption accounts for induced activity of Actinium. the difference in the law of disappearance of the scintillations for polonium as compared with that of the active deposit of actinium. (3) The initial drop in the decay curve supports the above hypothesis. (4) The hypothesis explains the observation of Geiger and Marsden that IO per cent. of the scintillations produced by the active deposit of actinium are double.
BLANQUIES.
(Comptes
of the
rendtis,