Value Of Such Materials Research Articles

Characteristics of a human diploid cell designated MRC-5.

THE stability and integrity of the human foetal cell strain WI-38, which has been well demonstrated in the past ten years1–3, and its susceptibility to viruses infective for man1,4, explain the value of such material for the isolation of viruses and in the development of vaccines5–8. We have developed another strain of cells, also derived from foetal lung tissue, taken from a 14-week male foetus removed for psychiatric reasons from a 27 year old woman with a genetically normal family history and no sign of neoplastic disease both at abortion and for at least three years afterwards. The criteria used for characterizing the cells are those recommended internationally2,9.

Some characteristics of aqueous slip formation

1. From the viewpoint of their reaction with water, all dispersed materials can be divided into acid and basic. The pH value of such materials has been chosen as a criterion of their reaction with water. 2. A mutual relationship has been established between the nature of various materials and that of the indispensable stabilizer. It is shown that the thinning of acid materials can best be performed by adding NaOH and that of basic materials, by adding HCl. 3. Idealized graphs have been plotted to show the dependence of slip viscosity,ζ potential, and casting density on pH.

Feeding Value of Silage

FARMERS must be able to judge the feeding value of their silage, and to meet this need the Ministry of Agriculture has issued Bulletin No. 50 in the “Grow-more” series. High-quality silage is a cake substitute and can only be obtained from the right crop, cut at the right time and properly ensiled. The colour, smell, texture and dry-matter content of material in this category are described, and recommendations given as to the rate at which it should be fed. If any of the requisite conditions is not fulfilled, the silage can only be used to replace hay, roots, or oat straw. The value of such material varies considerably according to the type of crop from which it is made, or to the conditions during ensiling, but suggestions are given as to the rationing of several of the low-protein silages. For the less experienced farmer, a useful table is included, in which the common faults in silage, their cause and the appropriate remedy are described, and if still further information is desired, application can be made to the county agricultural organizer.

The Preservation of Business Records: Why Business Records Should Be Preserved

Every business concern has to use records of many types. They are expensive to prepare, they soon lose their current value, and they tend to accumulate in large masses. Modern business destroys great quantities of records and correspondence every day because storage often seems expensive and unnecessary and because the future reference value of such material is not appreciated. It is neither possible nor desirable to keep all business records indefinitely. A business concern has more important things to do, and must avoid unnecessary expense. But selected material should be permanently preserved by individual firms because the historical information which it contains is of definite educational value (1) to the firms themselves, (2) to historians who are trying to study important aspects of human experience, and (3) to the general public which is served by business and which ultimately governs the conduct of business.

Tanning Materials of the British Empire

THERE is much truth in the old saying that there is nothing like leather; and one rejoices that the tanner continues to thrive in an age which has produced substitutes for so many of the common commodities and witnessed the decline and extinction of so many of the ancient crafts. The exceptional calls which were made upon the leather industry during the War led to an enormous demand for tanning materials, but even under the more settled conditions of the last few years the consumption has shown a steady increase. The total value of such materials used in Great Britain in 1928 was £2,413,000, of which more than half was imported from foreign countries? this position cannot be considered satisfactory when the supplies available within the British Empire are reviewed.

A survey of heat conduction problems

Several forms of thermal conductivity apparatus are described which have been devised for the study of diverse materials ranging from a sheet of mica to a wall section weighing half a ton. The materials are broadly classified into four groups: (1) Materials of very low thermal conductivity, such as cold storage insulators. (2) Materials supplied in the form of thin sheets and those employed in building construction. (3) Refractories and materials employed in furnace construction. (4) Pure metals and alloys. Samples of baked slab cork are shown with a conductivity as low as 0.00007 c.g.s. unit. The insulating value of such materials is due to the fact that they subdivide the air space into a large number of minute air cells. The theory of heat conduction through granular material is an interesting problem. An attempt to work it out mathematically has been made by M. Smoluchowski dagger. The wide divergence between the results obtained by experiment and those calculated from theoretical considerations indicate that the mechanism of the heat transfer from solid to gas is one which requires further study. In the testing of materials of low thermal conductivity by the hot plate method attention has to be given to heat leakage from edges and corners. The simplest procedure is to eliminate the by the use of a guard plate, but it is also possible to calculate an approximate correction for the edge effect when using the simple hot plate method. A mathematical problem awaiting solution with numerous practical applications is the adaptation of the method of conformal representation to three-dimensional problems. Sixty years have now elapsed since the publication of the important papers by Schwarz and Christoffel, and in this interval numerous papers have appeared demonstrating what a powerful tool conformal representation is for the solution of two-dimensional problems. Substances in the form of thin discs can be tested by the divided bar method, the correction for the thermal resistivity of the two mercury films being obtained by independent experiments using a thin disc of iron instead of the specimen. This apparatus is not well adapted for the study of poor heat-conductors, owing to the fact that the temperature drop across the specimen is then large and the gradient along the two bars small. The electrically heated plate, sandwiched between two discs of the material with water-cooled plates on either side, is an apparatus which can be adapted to various substances obtainable in sheet form. A form of this apparatus devised for the study of the of pressure on the flow of heat through a pile of paper-covered iron stampings is illustrated. In this test the thermal resistance across the laminations is measured. For the determination of the heat flow along the laminated material a bar about 15 in. long of square section, 2 in. by 2 in., is built up. One end is electrically heated, while the other dips into a pot of mercury carrying a cooling coil. From the temperature gradient and the heat flow the conductivity can be calculated. The apparatus for the study of refractories consists of a furnace made up of silit rod heaters which can raise one face of the slab under test to any temperature up to 1000° C. On the top of the slab is a water-flow calorimeter fitted with a guard ring. The calorimeter and guard ring are made of thick slab brass with grooves milled in the back surfaces for water circulation. To reduce heat transfer between calorimeter and guard ring the edges of the plates are chamfered off so that the edges on the brick are near together, whilst the rear parts are well separated. For the study of metals and alloys the guard tube method for the elimination of heat loss sideways is to be recommended in preference to Forbes' procedure. The space between guard tube and specimen is packed with a powder of low thermal conductivity. Both specimen and guard tube can be attached to a cylindrical block containing a heating coil. The heat flow is determined with a cooling coil fixed to the other end of the specimen. Water flows round the end of the specimen and the guard ring so that the same gradient is maintained automatically in specimen and guard tube. In some experiments the guard tube is dispensed with and the heat leakage through the lagging material calculated approximately. In the study of two groups of alloys - aluminium alloys and bronzes - it has been found that the two groups give values of the Lorentz coefficient approximating to the values for the pure metals which form the principal constituents of the alloys - namely, 5.5 for the aluminium alloys and 5.9 for the copper alloys.

Saturation Permeameter

The saturation permeameter is a device for speedy and accurate measurement of saturation value of magnetic material; that is, for measurement of the limiting value of intrinsic induction (ß) characteristic of that material. The permeameter in its present form is of the well-known bar-yoke type, with a magnetizing coil capable of producing a magnetizing force of H = 4500 g. without excessive heating. The permeameter is equipped with a compensating coil whose function is to compensate automatically for the spatial flux enclosed by the potential coil, so that the ballistic deflections indicate the saturation value without further computation or correction. The permeameter is available for accurate measurement of saturation value of such material as is saturated well within the working range of the permeameter, i. e., with a magnetizing force of H = 8000 g., or less, which includes all magnetic material used for electrical engineering purposes except those for permanent magnets and cobalt. The saturation permeameter is also available for approximately correct measurement of B or ß, for range of H below the saturation point as far down as H = 200 g. In speed of testing and accuracy of the measured saturation value, this permeameter surpasses all devices for saturation measurement developed heretofore.

Saturation permeameter

The saturation permeameter is a device for speedy and accurate measurement of saturation value of magnetic material; that is, for measurement of the limiting value of intrinsic induction (s) characteristic of that material. The permeameter in its present form is of the well-known bar-yoke type, with a magnetizing coil capable of producing a magnetizing force of H = 4500 g. without excessive heating. The permeameter is equipped with a compensating coil whose function is to compensate automatically for the spatial flux enclosed by the potential coil, so that the ballistic deflections indicate the saturation value without further computation or correction. The permeameter is available for accurate measurement of saturation value of such material as is saturated well within the working range of the permeameter, i. e., with a magnetizing force of H = 8000 g., or less, which includes all magnetic material used for electrical engineering purposes except those for permanent magnets and cobalt. The saturation permeameter is also available for approximately correct measurement of B or s, for range of H below the saturation point as far down as H = 200 g. In speed of testing and accuracy of the measured saturation value, this permeameter surpasses all devices for saturation measurement developed heretofore.

V.—The Wexford Gravels and their bearing on Interglacial Geology

The shell-bearing gravels of the county of Wexford have become so well known on account of their fossil contents that the boulder-clays associated with them have received scanty recognition. Very diverse statements have been made in regard to thè position of the gravels in the succession of superficial deposits, and they have, frequently been confused with the 'marl' which was extolled by early writers upon agriculture. Nearly all the references to the manurial value of such materials in Co. Wexford refer to this marl, that is, to a shelly and calcareous boulder-clay. The gravels, however, have been commonly styled 'manure gravels' by geologists, and R. J. Griffith, as far back as 1836, distinctly states that the shells are sometimes so very numerous “that the gravel is raised for manure”.