Vor,. 7, No. 3
TESTS I N ORGANIC CHEMISTRY
ljl5
These formulas represent members of the methane series 01 hydrocarbons: a. CsHu h. CmH21 c. CsHlo d. C,H,O e. CsoHlz3 2. These formulas represent esters: a. (C2Hr)~S03b. C H C l c. CSH5COOC2H, d. CHaCOCl e. GHsHSO*
1.
Sequence Type Two examples of the sequence type are given in Tests 2: and L'G TEST 25
A . To produce butyric acid from the ethyl ester of malonic acid one may pass through these steps. Number them in order. ,
. . .Saponification . . .Heat to remove COX
.. . . A d d N a . . . .Add '&HaBr
A . To obtain pure crystals from some impure material these steps may be carried out. Number them in proper sequence. . . Melting-point determination
. . .Choosing solvent . . . .Removal
. . . .Fractional crystallization . . . .Removal of residual solvent
of insoluble impurities
These tests are of course only suggestive of the various modifications which the objective examination may take in organic chemistry. By analysis of the subject matter to be covered, practically every portion of this branch of chemistry can be included in questions of the above types.
Reducing Dust Hazard of Granite Industry. Removal of air a t a speed of 1500 feet per minute, measured a t the surface of the ventilating hood, is thc standard for ventilating systems that will reduce the dust in the air of granite plants to a safe level, the U. S. F'nblic Health Service has announced as the result of its studies just completed. Dust in the various operations of the granite industry has long been s scrious hazard to workers' health. The disease of the lungs known as silicosis was found to develop as a result of prolonged exposure t o the granite dust through long periods of employment. Previous studies showed that when the air which the operator breathed had less than 10 million particles of dust per cubic foot of air, it was safe. Certain of the granite-cutting plants had ventilating systems which provided sufficient ventilation t o make the plants safe for the workers when the systems were properly operated, the recent investigations showed. Besides studying the ventilation systems in operation, the U. S. Puhlic Health Service conducted an experiment t o determine the exhaust velocity necessary a t the ventilating ducts t o keep the duet down to a safe limit. As a result of the experiment, the safe limit of exhaust velocity was determined to be 1500 feet per minute.-Science Sewice
