During these inspections information has been sought on the following points:

1. The causes in the various trades that give rise to the offensive effluvia complained of.

2. The chemical nature of these effluvia.

3. The methods taken, if any, by the manufacturers to prevent or 'lessen their production of nuisances.

4. The degree of compliance with the Governor's proclamation by those engaged in the offensive trades mentioned therein.

This division of offensive trades mentioned in the Governor's proclamation, will be used in this report to classify the information obtained on the above questions.

PETROLEUM REFINING.

This industry, the most extensive in the district, deserves a somewhat detailed consideration.

The objectionable features will be referred to, noting the steps in the process of refining in their order.

Fractional distillation of Petroleum.-This operation is conducted in large cylindrical retorts or "stills," connected with a coil of wrought iron pipe, submerged in a tank of water for the purpose of cooling. The first products of distillation are gases; at ordinary temperature they pass through the coils and escape without being condensed. The vapors soon begin to condense and the first distillate obtained has a gravity of about 95° Beaumé. As the distillation proceeds the products become heavier and when the gravity reaches 65° to 59° Beaumé, the stream of distillate is turned into the "burning oil" tank into which it is allowed to run until the gravity is about 38° Beaumé, when the stream is diverted into the "paraffine oil" tank, the distillation being continued until only tar remains.

This figure includes the uncondensed gases at ordinary temperature (Nos. 1, 2 and 3), the tar, and loss.

In actual practice one refinery does not make the entire list of distillates, but disposes of crude distillate to others for purification.

Odor of uncondensed vapors.-The escape of the light hydrocarbons produced during the first part of the distillation is now prevented by a simple system of hoods and suction conduits, which lead the gases

from each still down into its own fire, thereby burning them without offense.

Odor of crude distillate.-This is produced by exposure, in tanks with the covers open, in order to receive the benefit of sun-light and wind in bleaching and purifying the oil. The source of evil is entirely

unnecessary.

Odor in cleaning Stills.-This operation was a source of nuisance; after the last distillate has run off into the "heavy oil-tank," there yet remains in the still tar and some soft coke. The tar is first drawn off into closed tanks, and subsequently mixed with coal-dust for fuel. The still is then cleansed of remaining vapors by blowing in steam, as it is termed. This steam, with offensive vapors, was until recently allowed to escape into the air. But, by the same effectual method used in consuming the uncondensed gases, these offensive gases are now completely consumed, thereby removing a large factor in the combined nuisance of an oil refinery, as well as materially saving in the consumption of fuel.

Production of Smoke.-Improvement has been made in the abatement of this source of nuisance. In most of the refineries, the fires are started with wood and broken coal, and no "mixed fuel" (consisting of pea coal, dust and other refuse tar, and coke from the stills) is used until the fire is perfectly lighted. There are some refineries, however, in which this important matter is grossly neglected, and defective "stoking" renders, in all the refineries, the frequent or occasional production of an immense volume of smoke, which could be prevented by more careful superintendence of the stokers.

sweet

Treatment of the Distillate - Agitation with Sulphuric Acid. The crude distillate (as well as naphtha and lubricating oil) resulting from the fractional distillation as described, is next purified or ened" by thorough agitation in cylindrical lead-lined tanks or upright "agitators" with from 1 to 2 per cent, by measure, of the sulphuric acid of 66° Beaumé, The agitation is effected by blowing air through the liquid by means of a pipe extending nearly to the bottom of the tank. By this means the acid removes the offensive properties of the distillate, partially by carbonization as well as by chemical combination; and also, by virtue of its gravity. The impurities thus removed are1. The offensive characteristic odor of the crude distillate.

2. The tarry and gummy matters which would render the oil useless by the rapid incrustation of the lamp wicks,

3. The color, disagreeable to the eye.

tors.

After this thorough agitation, on standing, there separates a dark red, tarry liquid which is drawn off from the cone-shaped base of the agitàThis constitutes the well known "sludge " or "spent acid," as it is termed by the refiners. The oil is then washed with water; then with an alkali (usually caustic soda) thus neutralizing all remaining acid, and leaving the oil "sweet" and colorless, ready for the market."

Exposure of Sludge-Acid.—The effect of improper manipulation of this offensive product has been a great nuisance. In this important matter eleven of the thirteen refiners have united in adopting a system *Some refiners wash the oil again with water after treatment with alkali, and occasionally redistillation or exposure under glass to the sun is resorted to.