Drying Apparatus

In the laboratory, soil water content is measured by drying in the oven and with a pressure plate apparatus. Drying soil can change the form and species of components present, and for this reason, most soils are air dried carefully or at temperatures only slightly above room temperature before analysis. A number of different field measuring methods are used mostly to determine the amount of water available for plant use. 

There is very little if any low-boiling material when the reaction is carried out as described and care is taken to have the apparatus dry and to exclude moisture. 

Suspend 18 g acid-base-acid washed Chromosorb W in a mixture of 50 ml dried toluene and 25 ml tetrachlorosilane (TCS), treat it for 5 min. in an ultrasonic bath to remove air, filter off the solution after 4 hours at room temperature, rinse with dried toluene under exclusion of water to remove the TCS completely. While it is still excluded from atmospheric moisture, suspend the TCS treated support in a solution of 8 g PEG 4000 in 75 ml dried toluene for 48 hours at 50°C. Filter the PEG solution off and rinse the mass with toluene and methylene chloride successively, followed by extraction with methylene chloride in a Soxhlet apparatus. Dry the mass in a rotary evaporator at 60°C. 

A paper strip, suitably supported, dips at its ends into electrode vessels containing a buffer solution, acting as the electrolyte. The paper is soaked in the buffer, and the sample is applied at some point on the strip as a thin transverse streak (by the same method as used in paper chromatography). The electrodes are connected to a d.c. source, and field applied for a predetermined time see Section 3.3.4 for further details. The strip is removed from the apparatus, dried, and bands located—again as in paper and thin layer chromatography. 

The same apparatus is used as for synthesis C. In the dry Nj atmosphere of a glove box, a mixture of [NF4][SbFft] (37.29 mmol) and CsjlMnF ] (18.53 mmol) is placed in the bottom of a prepassivated (with CIF3) Teflon FEP (flu-oroethylene propylene copolymer) double U-tube metathesis apparatus. Dry HF (20 mL of liquid) is added at -78° on the vacuum line, and the mixture is warmed to 25° for 30 min with stirring. The mixture is cooled to -78° and... 

Zinc is a constituent of many common alloys, including brass, bronze. Babbit metal, and German Silver. It is used to make household utensils, castings, printing plates, building materials, electrical apparatus, dry-cell batteries and many zinc salts. It is also used to... 

The layer thickness of the dry cellulose is never the same as that set on the spreader. A rule of thumb says that cellulose layers shrink to about half of the slit breadth set on the apparatus. Dry layers of about 0.12 mm are particularly good for most separations and reveal most convincingly the advantages of thin-layer chromatography. Thicker layers up to 0.6 mm of fibrous cellulose powder and up to 1 mm of micro-crystalline powder, can be made without cracks. 

Once it begins, the bunsen can be turned off. Iron(lII) chloride forms as a vapour, and solidifies in the cold collecting jar. Calcium chloride absorbs moisture, so it keeps the apparatus dry. 

Using the above apparatus, dry ammonia is passed over heated copper(II) oxide. The gases given off are passed through a cooled U-tube. A liquid (A) forms in the U-tube and a colourless gas (B) collects in the gas jar. 

The lithium alkyls are extremely reactive, being sensitive to oxygen and to moisture. Care is therefore needed to use dry apparatus, dry solvents and to exclude air by means of dry oxygen-free nitrogen. Generally,... 

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