Cold boiling

Weigh out accurately 0.14-0.15 g of pure dry potassium iodate, dissolve it in 25 mL of cold, boiled-out distilled water, add 2 g of iodate-free potassium iodide (Note 1) and 5 mL of 1M sulphuric acid (Note 2). Titrate the liberated iodine with the thiosulphate solution with constant shaking. When the colour of the liquid has become a pale yellow, dilute to ca 200 mL with distilled water, add 2 mL of starch solution, and continue the titration until the colour changes from blue to colourless. Repeat with two other similar portions of potassium iodate. 

Note. If preferred, about 0.20 g of potassium dichromate may be accurately weighed out, dissolved in 50 mL of cold, boiled-out water, and the titration carried out as detailed above. 

To 20 gms. (1 mol.) of cold boiled-out 67% nitric acid, 2 gms. of urea in 15 gms. (excess) of absolute alcohol are added, and half of the mixture distilled off on a water bath in a tubulated retort attached to condenser and receiver. 40 gms. of similar nitric acid mixed with 30 gms. of absolute alcohol, and containing 0-5 gm. of urea, are now allowed to drop in through the tubulus from a tap funnel at the same rate as the liquid distils. Water is added to the distillate, the ester which separates is washed several times with cold water, dried over calcium chloride, and distilled from a water bath, the fraction 84°—88° being retained. Care must be taken in this experiment, as the ester is liable to explode when quickly heated. All operations should be carried out behind a metal screen. 

Acidity.—2 grams of the dry, powdered bread are treated in a 500 c.c. flask with about 300 c.c. of water which has been boiled for some time and is still boiling. The flask is shaken at frequent intervals until the liquid is cold, boiled water being then added to the mark and the whole well shdken, left for a time and afterwards filtered 250 c.c. of the filtrate (corresponding with 1 gram of the bread) are titrated with N/io-potassium hydroxide in presence of phenolphthalein. 

Individual HEPA filter efficiencies are established by an exacting challenge of the filter frame and medium, usually incorporating a cold-boil, polydisperse aerosol of dioctylpthalate (DOP) or equivalent, which is introduced into the upstream plenum-side of the filter in a manner that ensures even distribution of the test aerosol behind the filter, at its rated airflow. 

A solution of 20 g. of KaW lg in 150 ml. of cold, boiled water is prepared and treated on a water bath with 65 g. of KCN powder this causes oxidation to W (IV), and the green color of the solution changes to red. The KCN should be added very carefully (shaking) over a period of 5 to 10 minutes. 

To dispose of the apparatus safely, place the cold boiling tube in a large bowl of water to destroy the magnesium silicide. This may ignite due to the production of silanes which combust in air. 

Avoid contact of the skin with liquid air or its cold boil-off gas. Flush liquid air spills with water to accelerate evaporation. Because of the preferential evaporation of nitrogen, initially... 

Avoid contact of the skin with liquid neon, krypton, and xenon or their cold boil-off vapor. 

Boric acid, 4% w, dissolve 40 g boric acid (H3BO3) Analar in 1000 ml distilled water contained in a 2 litre round bottomed flask. Boil for 20 minutes to expel carbon dioxide. Connect a carbon dioxide absorbing guard tube and cool. Transfer to a 1 litre volumetric flask. Make up to 1 litre with cold boiled out distilled water and mix. 

Treat the substance with dilute aqueous sodium hydroxide. Ammonium salts evolve ammonia in the cold. Boil the solution to drive ofif all ammonia, cool, add a slight excess of dilute sulphuric acid, and very carefully evaporate to dryness. Examine the residue for nitrogen by Lassaigne s test. (Part of the residue may be submitted to the test for sulphonic acids, given below.)... 

Thermally efficient design of a storage system consists of reducing A heat in-flows to a minimum, while ensuring in the design that B heat in-flows are absorbed by the cold boil-off vapour. Furthermore, any conversion of A heat... 

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