Determination Of Specific Gravity Research Articles

A new micro-pyknometric method for the specific gravity of heavy solids; with a note on the accuracy of specific gravity determinations

The determination of the specific gravity of a solid which is only available in small quantity has always been a difficult problem in cases where the suspension method fails, either because the solid is too dense, or because it dissolves in or reacts with the heavy liquids available. It is hoped that the following method will be found a useful addition to the numerous methods which have been proposed from time to time to meet such cases. References to most of these methods are given at the end of the paper. Neither the new method nor any one of the older ones is universally applicable, and the best method for any particular case will depend on many circumstances.

Determination of Specific Gravity

Determination of Specific Gravity

Determination of Surface Tension and Specific Gravity of Crude Oil under Reservoir Conditions

In view of the importance of the application of scientific principles to theproduction of oil from the reservoir, the Production Staff of the Anglo IranianOil Co. (late Anglo-Persian Oil Co.) has been engaged for some years on anintensive program of research on the physical properties of crude oil. Problemsinvolving the retention of crude oil in capillaries and fine fissures demandedfor their solution a knowledge of the surface tension and specific gravity ofthe crude under reservoir conditions, and it is the purpose of this paper todescribe briefly the methods adopted for the determination of these properties, and to present the more important results. A detailed article was published involume 1 of the World Congress Proceedings (1933). Surface-tension observations on crude oil regassed at high pressures withnatural gases have been made in the past by Beecher and Parkhurst and Swartz, but up to the time of the investigations in Iran no one seems to have carriedout experiments with gas-saturated crude direct from the reservoir and kept atits original pressure. Results obtained in this manner are obviously of greaterpractical value for solving problems connected with the reservoir. Method of Measurement No apparatus for the measurements, under the pressure conditions involved, wasavailable, and a suitable instrument had to be designed and constructed in theFields workshops. Careful consideration of the matter led to the adoption of amethod for measuring the surface tension which did not involve a knowledge ofthe specific gravity of the oils under the working conditions: the main reasonfor this being that up to that time no accurate determination of the specificgravity had been made under these conditions.

Forensic Chemistry and Scientific Criminal Investigation

“FORENSIC CHEMISTRY” is not a very intriguing title but, interpreted in the generous spirit of the author of this work, it covers a varied range of phenomena, and it is certainly interlinked with some of the most tragic dramas of the century. The book may be considered under two aspects. It is primarily a textbook for the expert witness, or for him who would aspire to reach that third and highest plane. For him Mr. Lucas gives clear and meticulously careful advice on the manner of preparation of a report, and macroscopical, microscopical and general and special analytical methods are described which cover almost every happening in the annals of crime. The help that physical science may give is not forgotten, and X-rays, ultra-violet and infra-red photography, and methods for the determination of specific gravities and refractive indices are all pressed into service.

The determination of specific gravity: III. Influence of the spinning process on the specific gravity and on the adsorbing power of acetate silk

The determination of specific gravity: III. Influence of the spinning process on the specific gravity and on the adsorbing power of acetate silk

The interaction of clay with water and organic liquids as measured by specific volume changes and its relation to the phenomena of crumb formation in soils

The densities of clay particles determined by the specific gravity bottle method vary somewhat according to the liquid used. Thus water, alcohol, and benzene all give slightly different values. The results show that some condensation of the liquid on the surface of the particles usually, if not invariably, takes place, indicating a certain amount of interaction between the clay and the liquid. The investigation described in this paper shows that this interaction depends partly on the exchangeable bases associated with the clay, and partly on the molecular constitution of the liquid. The relations are as follows : (1) No evidence could be obtained of interaction between clay and non-polar liquids. (2) Interaction took place in all the polar liquids examined. Its amount was measured by the reduction in specific volume of the clay as compared with its volume in tetralin, a very convenient non-polar liquid for specific gravity determinations. This reduction in specific volume is approximately proportional to the number of exchangeable cations present, figs. 10, 11, and to the mean density of their surface charge, Table IV.

Societies and Academies

Societies and Academies

Determination of specific gravity of paraffin

Determination of specific gravity of paraffin

The determination of specific gravity: I. The specific gravity of acetate silk

The determination of specific gravity: I. The specific gravity of acetate silk

The determination of specific gravity. II. The influence of dyeing and of superficial saponification on the specific gravity of acetate silk

The determination of specific gravity. II. The influence of dyeing and of superficial saponification on the specific gravity of acetate silk

Overflow during Vulcanization. Its Dependence upon Inactive and Active Fillers, and Errors in Previous Calculations of the Specific Gravity of Vulcanizates Resulting from It

Abstract 1. Raw rubber undergoes no change in volume during vulcanization. 2. Whenever it is vulcanized with sulfur there is an increase in volume. 3. Every inactive filler influences the overflow (increase in volume) in a characteristic way during vulcanization. 4. An increase in the proportion of a given inactive filler influences the overflow curve in a manner characteristic of the filler concerned. 5. Different inactive fillers influence the overflow in various ways. 6. Active fillers influence the overflow curve in a different manner from inactive fillers. 7. An increase in the proportion of a given active filler influences the overflow curve in a manner entirely characteristic of the filler concerned. 8. Different active fillers influence the overflow in quite different ways. 9. The specific gravity of a vulcanizate with sulfur is always less than the specific gravity of the corresponding unvulcanized mixture. 10. All calculations of specific gravity heretofore made in the rubber industry and theories related to them are incorrect because they are based on the false assumption that no increase in volume occurs during vulcanization. 11. Specific gravity determinations of mixtures must be based on overflow determinations.

THE EFFECT OF DIFFERENT FLUXING OXIDES ON THE CONSTITUTION OF PORCELAIN1

This article deals in a general way with the constitution of siliceous porcelain. The influence of the different fluxing oxides on the formation of the glass phase is indicated by solubility and specific gravity determinations as well as by microphotographs.

Attempts to Visualize the Gail-Bladder of the Rabbit with Tetraiodophenolphthalein

In previous work we were unsuccessful in attempts to record a gall-bladder contraction in the rabbit on the injection of cholecystokinin. It was reasonable to suppose by analogy from Graham's and Cole's work, that we would be able to study the problem roentgenologically, after the administration of sodium tetraiodophenolphthalein. Graham, Cole and Copher report that they have visualized the gall-bladders of rabbits after the subcutaneous injection of sodium tetrabromphenolphthalein, but add that these shadows were faint and inconsistent. We hoped to get more consistent results using intravenous injections of tetraiodophenolphthalein. Because of our early failure in 4 rabbits to get shadows with the usual doses of 0.2 gm. per kilo, we increased the amount. Four rabbits were given 0.3 gm. per kilo, one of which showed toxic symptoms. One of 2 rabbits given 0.4 gm. died in 4 hours. Twenty-four rabbits were given the usual dose of 0.2 gm. per kilo, which proved fatal in 2 cases. This is in accord with Whitaker and Milliken, who studied the toxicity of tetraiodophenolphthalein and tetrabromphenolphthalein, finding that 0.24 gm. is the largest single non-toxic dose for rabbits, Because of the possibility of missing the time of maximum concentration, which in dog and man is after 14 hours, the dye was given to fasting animals, and pictures taken every 2 hours until 40 hours after the injections. We were uniformly unable to obtain shadows of the rabbit's gallbladder. As control experiments we injected the same dye, in the same dose (0.2 gm. per kilo) in dogs and sharply defined shadows were obtained. Because of this lack of concentration of the dye in the rabbit, we took specific gravity determinations. We found the rabbit's gallbladder bile to have a specific gravity of approximately 1.048, which is within the lower range of the specific gravity of gall-bladder bile of man and dog.

Rapid determination of specific gravity of semi-solid bituminous substances

Rapid determination of specific gravity of semi-solid bituminous substances

A simple and accurate constant-volume pyknometer for specific gravity determinations

Experience with the usual types of glass pyknometers long ago convinced the writer that these instruments as ordinarily used are subject to considerable errors and may be quite unreliable when dealing with small quantities of material, It is true there are forms intended to be used in conjunction with a very precisely regulated water-bath which are capable of giving results of high accuracy, but this method of determination at constant temperature involves too much time and trouble for routine mineralogical work. But no matter what the design of glass pyknometers, and their variety is legion, in actual practice they suffer in common from tile defects of the material of which they are constructed.The heavy-solution method is inconvenient ; it cannot be used for the heavier materials and there is often danger of contaminating the material which may be intended for analysis.

Variations in the Composition of Milk: a Study of the Results of Analysis of Six Hundred and Seventy-six Samples of Milk (each Sample being the Milk of one Cow) from Cows of various Breeds throughout Scotland in 1921–22

THE Inter-departmental Committee appointed to report on the regulations, etc., governing the sale of milk in Scotland arranged for a large number of samples of milk taken at random from individual cows to be analysed. No particular breed was selected, nor was any account paid to the period of lactation, feeding, age of animal, etc., the only consideration being to ensure proper and thorough milking and the taking of a representative sample. In all, 676 samples of milk were dealt with, the samples being both from morning and evening milkings, with a small proportion of midday samples (the latter, however, not included in the statistical analysis). The examination of the samples covered the usual determinations of specific gravity, fat, solids not fat, and in addition the estimation of nitrogen, lactose, ash, refractive index and freezing-point.

A graphical method for the rapid correction of specific gravity determinations

It has long been recognized that if specific gravity determinations are to be accurate to a unit or two of the third decimal place corrections must be applied for the error due to the circumstances (i) that the weighings are made in air instead of in a vacuum, and (ii) that the temperature at which the determinations are made usually differs considerably from the standard temperature of 4° C.

THE SPECIFIC GRAVITY OF THE URINE

In a recent number of the Archives of Internal Medicine1appeared a paper by T. Addis and Marjorie G. Foster under a title identical with the one given to this communication, wherein were offered experimental data which seemed to them to lead to the following conclusions: The specific gravity of the urine of normal persons was measured under varying conditions designed to place a strain on the concentrating activity of the kidney. It was found that not even an approximate idea of the work of the kidney in the excretions of solids could be obtained from the results. It is therefore concluded that specific gravity determinations cannot form part of any method intended to measure the amount of secreting tissue in the kidney. Although it appeared to us evident that the data as presented had been wrongly interpreted, we appreciated the possibility of correct conclusions in spite of false premises

Some density determinations

It was required to determine the densities of small quantities of metallic elements to an accuracy of about one part in 10,000, and this paper is an account of some of the work undertaken to reach that end. In the course of the work, the densities of the following substances have been determined :─ (1) Carbon tetrachloride. (2) Ethylene dibromide. (3) Cadmium. (4) Lead and isotopic lead from uranium ore. Kahlbaum who has made the most exhaustive study of the density of metals, states that the determination of specific gravity of metals is a delicate matter which can only be effected with success on large quantities of substance, and one cannot attribute to the result the general character of a physical constant for the metal; the determined value belongs exclusively to the sample on which the determination is carried out. These statements are in our opinion too sweeping ; but in this paper it is only intended to describe an improvement in density measurements which renders possible determinations with accuracy on comparatively small samples, and to give a few illustration of the effectiveness of the method.

The indicator method for the determination of coefficient of diffusion in gels, with special reference to the diffusion of chlorides

Since the original investigations of Thomas Graham on the diffusion of dissolved substances in water a number of methods have been evolved and used for the determination of coefficients of diffusion of solutes in water. The essential Feature of all these methods is the estimation of the quantity of dissolved substance after the lapse of a definite time in different lasers of a cylinder of water through which the solute is diffusing, the calculation of the coefficient then being made on the assumption of Fick's law, which defines the coefficient of diffusion as D in the equationdQ = -DA δc/δxdtwheredQ is the quantity of solute diffusing through a cross-section of the cylinder in the time at a point where the concentration gradient is δc/δxand A is the cross-section of the cylinder. A variety of methods have been used for estimating the concentration of the solution at different levels, these methods including chemical analysis of the lasers, specific gravity determinations, optical methods, such as determination of refractive index or optical rotation, determinations of electrical conductivity, and other electrical methods. These methods for the most part require special apparatus, and the determinations are not always easy to make. These are not, of course, to be regarded as drawbacks, but a glance at the results obtained by their means as summerised, for example, in Landolt and Börnstein's tables, is sufficient to give an impression of unreliability since the determinations of different workers often show very considerable divergence.