Fumes definition

Definition of the terms fume, smoke, dust and grit... 

Place (he bottle with contents in a chamber maintained at 65.5°il°C (See Fig oa p 28 of Ref 12 and on p 49 of Ref 13), the air in which is preferably maintained in constant circulation After (he bottle with contents has been heated for 24 hrs, reseat (he stopper. Make daily observation of the appearance of the sample and note the number of days required to cause (he liberation of visible reddish or brownish fumes of oxides of nitrogen Note It has been customary to consider any proplnt having a test value of 90 days or less to be of definitely impaired stability and any proplnt having a test value of 20 days or less to be sufficiently unstable as to require destruction or salvage... 

Although the substance of the composition H2S207 is capable of definite existence, the commercial products deviate from the composition expressed by the formula and contain variable quantities of sulphuric acid with pyrosulphurie acid or of pyrosulphuric acid with sulphur trioxide. For the purpose of including all varieties of impure pyrosulphurie acid, the somewhat vague terms oleum, fuming sulphuric acid and Nordhausen sulphuric acid are advantageous. 

Chemical Properties.—Pyrosulphuric acid, whether pure or mixed with excess of sulphuric acid1 or sulphur trioxide, readily undergoes decomposition into sulphuric acid and the trioxide indeed, the fumes evolved at the ordinary temperature are due to vaporisation of the trioxide from the molten acid or its solution in sulphuric acid. On heating the acid, sulphur trioxide is expelled until the mixture of sulphuric acid and water of minimum vapour pressure (98-3 per cent, sulphuric acid) remains. It is owing to this behaviour that pyrosulphuric acid and fuming sulphuric acids in general have no definite and constant boiling temperature. 

Berkhout Stability Test, designed in the artillery laboratory at Hembrug,Holland, consists in heating samples of NC or propints in weighing bottles at 95°, 105° or 110° and noting the loss of wt in a definite period(such as 72 hrs), as well as the time required for evoln of red fumes. The heating is conducted in a specially designed thermostatically controlled oven. Two models of such ovens are described in Ref 1 (Compare with Jacque Test and with Sy Test) Refs 1)J.D.Berkhout,SS 17,33 4(1922) CA 16, 2602(1922) 2)Reilly(1938),85... 

Fume cupboards must be kept free from surplus chemicals and discarded apparatus. If stocks of noxious chemicals which are in frequent use have to be stored in a fume cupboard they should all be assigned to one which is set aside for this purpose and is properly fitted with shelving. Chemicals which are carcinogenic, but the use of which is permitted, are always retained in a main store in specially provided sealed cabinets definitive authorisation is required for their use. 

Although no definite data are available concerning the toxicity of boron flouride, users should exercise caution and avoid breathing the fumes. The toxic effects of hydrogen fluoride and alkali fluorides are well known, boron fluoride reacts with... 

Burning herbs to ash is easy enough over a small propane stove, but there are a few problems. First there is the smoke and smell, sure to attract the attention of your neighbors and elicit moans and groans from other people of your household. Unless you have a good fume hood, this is definitely an outdoor activity. Secondly, there are some materials which refuse to get very white at all. There is a simple method we can use, called the leaching process, to obtain the salts in a purified form. 

Chemical Hazards. Chemical hazards are many and varied. It should be taken for granted that any chemical substance taken by mouth or inhaled is toxic until and unless definite assurance has been given to the contrary. Reactions that produce toxic fumes or vapors or entail risk of fire should always take place in a fume hood. As a matter of standard safety practice, never pipette any liquid or solution by mouth use a rubber pipetting bulb. Another insidious hazard is that of vapors from organic solvents. Such solvents should not be used indiscriminately for cleaning purposes, and spills should be avoided. Good ventilation is important. 

SAFETY PROFILE A very dangerous fire and explosion hazard when exposed to heat, flame, shock, or oxidizers. It is a powerful high explosive. Nitrostarch is not a definite compound, but a mixture of various nitric acid esters of starch with different degrees of nitration. When heated to decomposition it emits toxic fumes of NOx. See also NITRO COMPOUNDS. 

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