Variation In Specific Gravity Research Articles

The Hydraulic Shape of Sand Particles

ABSTRACT The shapes of sand particles that affect their hydraulic properties in a moving fluid during entrainement, transport and deposition are closely approximated by their dynamic shape factor (DSF), the squared ratio of fall velocity of the particle to the fall velocity of its nominal sphere. We determined the DSF values for 126 specimens of 15 common heavy minerals (magnetite, tourmaline, garnet, etc.) by weighing each grain and by measuring its fall velocity in water. The results are compared with geometric shape measures obtained from the triaxial dimensions of each particle. The geometric shape measures all show a high correlation with the DSF. Lines of equal DSF on a dimensionless (CD-R) plot are shown to be logarithmically distributed according to the function DSF=Z=(8F/v2)/(CDR2), of gradient, Z=Z(1/CD2+4/R2)1/2. Among particles of the same mineral, shape can influence their hydraulic properties (drag coefficient) to about the same magnitude as variation in specific gravity among the heavy mineral species. Thus, variation in shapes of heavy minerals can produce about the same differences in size frequency distribution as the expected variations in specific gravity. The effects can be great. If minerals are to be used to discriminate sedimentary environments, or to establish consanguinity of heavy mineral suites, their hydraulic shapes should be accurately measured, and the effect of shape on the mineral distribution evaluated.

An Electromagnetic Method of Measuring the Temperature Variation of Specific Gravity of Liquids by the Use of the Float Containing a Permanent Magnet

An Electromagnetic Method of Measuring the Temperature Variation of Specific Gravity of Liquids by the Use of the Float Containing a Permanent Magnet

THE EFFECT OF SEVERAL VARIABLES ON THE SPECIFIC GRAVITY OF SECOND-GROWTH DOUGLAS FIR

Second-growth stands of mixed Douglas fir and western hemlock produce wood that varies considerably in quality, expressed as specific gravity, depending upon the factors of position in the stem, crown class and site index. Data were obtained from sample Douglas fir trees removed in a thinning operation on the University Research Forest, Haney, British Columbia. Samples represent three levels in the stem (stump, one-third total height and merchantable top), three major crown classes (Dominant, Codominant and Intermediate) and site indices from 93 to 160.It was determined that wood at the base of the tree was more dense than at the higher levels, although this difference failed to show significance for the better sites. Considering the differences, at the same levels, between trees of the three crown classes, Dominants had significantly lower values of specific gravity than either the Codominants or the Intermediates. No significant differences occurred between the latter two classes. When the variable of site is tested, it is found that the "Good" sites have significantly lower specific gravities than do the "Average" sites, for comparable sections. The interaction between site and crown class reveals that the differences above hold for the mean of all sites, and for "Average" sites, but that on "Good" sites no significant difference exists between any of the crown classes.In managing second-growth stands of this nature the forester should keep in mind the variation in specific gravity that will occur. He can regulate rate of growth of individual trees and of stands, within limits, so as to produce wood of the desired quality.

Variations in specific gravity of potatoes

Over 20,000 tubers of 6 varieties of potatoes obtained from 10 different states were graded individually for specific gravity. Varietal differences were noted in the specific gravity values. Katahdin showed the greatest variability and Irish Cobbler and Chippewa the least. The variability in specific gravity as shown by the standard deviations indicates that some lots and varieties are more adaptable than others to commercial separation into different specific gravity lots. The moisture content of the air in the storage rooms is an important factor controlling changes in specific gravity during storage. Potatoes stored at relative humidities of approximately 90 per cent showed slight changes in specific gravity during storage but lower humidities caused noticeable changes. Varieties differed materially in shrinkage and in their changes in specific gravity during storage.

Petrographic analysis of coal by the particle count method

Quantitative determinations were made of the banded ingredient composition of a number of domestic stoker coals prepared for combustion tests from large lot samples of small-size coal procured at 15 Illinois coal mines.The determinations were made by identifying and counting the discrete coal particles in selected samples using the petrographic technique which is commonly used to assay performance in ore dressing operations.A standard procedure for the analysis was developed which included close control of all steps in selecting the sample, crushing to free coal components into discrete particles, and size classifying the particles by mechanical screening. Strict criteria were adopted for identifying the coal particles.The results of the petrographic analyses which were of special interest in connection with the combustion tests concerned the effect of coal cleaning processes upon the proportion of banded ingredients. An increase in vitrain content of the cleaned coal was usually noted but concentration of this ingredient was never of considerable amount. The analyses also showed there was no great concentration of vitrain in the lots of small-size coal secured from the mines. Previously it had been thought that vitrain by virtue of its friable nature constituted a major proportion of the screenings produced in coal mining and preparation.During the course of the work certain incidental investigations were carried on concerning the effect of differences in hardness of the banded ingredients on size distribution when more or less pure ingredients were crushed under controlled conditions. The variation in specific gravity of the banded ingredients and the effect of this variable property in separating or concentrating coal ingredients by use of heavy liquid media was investigated. The paper discusses reliability of this method of petrographic analysis of coal and reports certain experiments made to determine degree of accuracy achieved.

A Geiger-Muller Counter for Measuring the Beta-ray Activity of Liquids, and its Application to Medical Tracer Experiments

A G-M counter of the jacketed tube type for β-ray measurements on liquid samples is described, together with a convenient means of mounting in a lead shield. It is shown that the counting rate obtained when the counter is filled is proportional to the concentration of radioactive substance in the solution. Methods for applying corrections for errors due to dead time of the counter and for variations in specific gravity of the solution are given, together with a calibration curve showing the absolute efficiency of the counter for various radioactive isotopes. The counter has proved useful for measurements of the radioactivity of whole blood, plasma, urine, etc., in medical tracer experiments.

A HIGH FLUID INTAKE IN THE MANAGEMENT OF EDEMA, ESPECIALLY CARDIAC EDEMA. II. CLINICAL OBSERVATIONS AND DATA

Excerpt It is only in the last 50 years that the limitation of fluids in the presence of edema has been taught and practiced so universally. Earlier clinicians noted that the theoretical fear of wa...

Relationship of Specific Gravity and Shell Appearance to the Hatchability of Fertile Turkey Eggs

PRELIMINARY studies during the latter part of the 1942 hatching season indicated that specific gravity and shell appearance might be considered as measurements of hatchability of fertile turkey eggs. Since only a small number (150) eggs were involved, it was decided to repeat the study throughout the 1943 hatching season.A search of the literature revealed that apparently no previous work had been done to determine the relationship between specific gravity and the potential hatching power of turkey eggs. Mussehl and Halbersleben (1923) found a small but significant correlation between the specific gravity of the whole chicken egg and hatchability. The specific gravity of the shell was found to be twice that of the egg contents, from which it was assumed that variations in specific gravity were due principally to the differences in shell thickness. Munro (1940) found a distinct curvilinear relationship between specific gravity and egg hatching power for .

Certain Physiological Changes Accompanying Prolonged Mental Reaction

In an attempt to note the extent and to find the limits of certain suspected physiological changes produced during periods of prolonged mental effort, several series of carefully planned experiments were undertaken involving 3 subjects familiar with the solution of mental arithmetic problems. The task was uniform throughout and consisted in the solution of multiplication of 4 numbers by 4 numbers from memory alone. The level of metabolic rate was measured by oxygen consumption using the Graphic Metabolism machine. Changes in the blood elements, erythrocytes and leucocytes and changes in hemoglobin content were checked in the usual manner by use of the hemocytometer and the hemoglobinometer. Conspicuous changes in excretory products were determined by routine urine analyses, involving variations in specific gravity, reaction, occurrence of albumin and sugar, di-acetic acid and acetone. Five specific tests were made on each of the subjects, the first series to establish the “norms” without mental effort. Th...

The Volume of the Cream Layers Forming on Holstein and Jersey Milk

Summary 1.The comparative creaming properties of milk may vary according to the procedure followed in making the tests. For greatest uniformity and the exclusion of unknown factors the milk was set for creaming within a few minutes after milking in ice water at 2.8° to 4.4°C. The cream layers of different samples showed variations in the cream layer volume and the distinctness of the cream line after two or four hours which were less pronounced after twenty-four hours. 2.The mean depth of the cream layers forming on normal milk from Holstein and Jersey cows was directly proportional to the percentages of fat which they contained. The percentage which the cream layer represented of the total volume of milk was about 4.1 times the percentage of fat. 3.The variations in the cream layer volumes forming on individual samples of Jersey milk were greater than those for Holstein milk. This difference was especially noticeable after two and four hours of creaming. 4.The milk from an individual cow did not possess uniform creaming properties from milking to milking although there was a tendency for the milk from certain cows to give either large or small cream layer volumes or a high percentage of no layer cases. 5.The cream layer volumes on the samples of milk used in these tests were not affected by the season of the year in which the milk was produced. The milk from Holstein cows remained most uniform throughout the year. 6.Variations in specific gravity of milk were not related to changes in creaming properties.

A NEW METHOD OF INTERPRETATION OF THE RENAL FUNCTION TEST MEAL

In a previous paper 1 we discussed the renal functional test meal, the interpretation of renal function as judged by specific gravity variation of the two hour specimens and character of night urine, and offered clinical evidence purporting to illustrate the influence of several extrarenal factors 2 on the test meal reaction. These extrarenal factors interfere considerably with the uniformity of response to the test meal by the same individual, at least upon viewing the responses in the manner heretofore suggested by Mosenthal. Subsequent to the publication of our study, Mosenthal 3 reported further studies in renal response to diets in which he felt obliged to revise his previous dicta as to evidences of normality and the significance of certain deviations therefrom, although still adhering to volume and specific gravity as the essential criteria of renal function. The nature and direction of his revision can be gleaned from an inspection of Table 1,

III.: Temperature and Specific Gravity Variations in the Surface Waters of Departure Bay, B.C.

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