217 
PARK AND CEMETERY. 
THE USE OF OIL EMULSIONS ON MACADAM ROADS 
The treatment of macadam roads 
with mixtures and emulsions of oils 
was begun in Lincoln Park, Chicago, 
during May, 1907. The roads for 
the most part are constructed of 
limestone macadam, but owing to the 
excessive and fast increasing auto- 
mobile traffic, it was found necessary 
to resurface sometimes twice a year. 
Whenever water collected on the sur- 
face of the road, consequent soften- 
ing would occur, and this soft ma- 
terial would be pumped away by the 
vacuum formed under the fast mov- 
ing automobile tires, causing deep 
holes. It was found very difficult to 
sprinkle with just the right quantity 
of water, so that no excess would 
show on the surface. During hot, 
dry days the dust would arise within 
a few minutes after the sprinkling 
cart had passed. The cost of sprink- 
ling averaged ten cents to fourteen 
cents per square yard per year, and 
at best, the dust was laid only about 
eight hours of the day. 
In experimenting with asphalt oils, 
the paramount idea was to lay the 
dust, and whatever lasting properties 
the material would give to the road 
metal was a secondary consideration. 
Experiments were started with Cali- 
fornia asphaltum, 98 per cent pure, 
bought of the California Sales Agency 
at $30 per ton or about ten cents per 
gallon. Sections of road were built 
with the pure- asphaltum oil incor- 
porated in the road metal, as well as 
being m.erely sprinkled upon the sur- 
face in the form of an emulsion with 
soap and water. In either form the 
material proved too sticky to warrant 
further use. Experiments were con- 
tinued, using Kansas and Kentucky 
fuel oils of different specific gravi- 
ties, but with minor success, as there 
seem.ed to be a lack of sufficient 
body to maintain a wearing surface. 
A mixture of two or three oils was 
then tried, and at last results war- 
ranted the adoption of a mechanical 
mixture or emulsion formed by the 
use of soap and hot water with the 
California asphaltum, previously de- 
scribed, and a Kansas fuel oil of 
about 28 specific gravity, purchased 
from the Standard Oil Company at 
three and a half cents per gallon. A 
great deal of care was found necessary 
in securing a soap which would work 
best with the water at hand. For the 
hard lime water of Lake Michigan 
the “Tak-a-nap” brand, a soft naptha 
soap manufactured by the Thayer & 
Hovey Soap Company of Darby, Pa., 
gave the best results. The emulsion 
when applied to the road surface 
does not become sticky, on account 
of the lubricating properties of the 
Kansas oil, but on the contrary, pre- 
sents a malleable, rubber-like cush- 
ion, which rolls down to a smooth 
surface under automobile traffic. It 
penetrates into the road metal suf- 
ficiently to give the desired bond, 
and the surface retains sufficient ad- 
hesive properties to cause dust par- 
ticles to combine with the road sur- 
face for a considerable length of 
time. The road assumes a dark seal 
brown color, restful to the eyes, and 
emitting no disagreeable odor, such 
as is commonly noticed on oiled 
roads. Traffic may continue unmo- 
lested while the oil is being applied, 
and no bad results have been notice- 
able on rubber tires or vegetation. 
The mixing plant consists of a se- 
ries of three 200-gallon hogsheads, 
set close together on end with their 
top heads removed. These hogs- 
heads are connected at the bottom 
with three-inch pipe and gate valves. 
In each of these receptacles are pipes 
for live steam and cold water. From 
the bottom of the hogsheads are con- 
necting pipes leading to a steam 
pump of about 40-gallon capacity. 
Arrangements are made so that the 
material can be pumped through any 
one of the hogsheads back into the 
same or other compartments through 
a reduced nozzle, or so that the ma- 
terial may be pumped from the oil 
delivery wagon to any of the recep- 
tacles, or from one of the receptacles 
into a sprinkler, which is used in ap- 
plying the emulsion to the road. 
In making the emulsion, sixty gal- 
lons of water are drawn into two of 
the hogsheads, the third hogshead 
being disconnected and reserved for 
heating water for subsequent use. 
Live steam is then turned on, and 
the water brought to a boiling point. 
Fifteen pounds of soap is then added, 
and the water allowed to boil five 
minutes longer. Sixty gallons of the 
Kansas oil is then added, and the 
mixture allowed to pass out of the 
bottom of one hogshead, through the 
steam pump back into the top of 
hogshead number two, through the 
agitating hose for about five minutes, 
when one-half barrel of California 
asphaltum is added, and the whole 
mixture allowed to emulsify for 
twenty minutes longer. It is then 
pumped into a distributing sprinkler 
of 800-gallons capacity, fitted with an 
adjustable cup discharging attach- 
ment. After receiving the stock so- 
lution, the sprinkler is filled to its ca- 
pacity with boiling water. Eight hun- 
dred gallons of the emulsion will 
cover approximately four thousand 
square yards of road surface. It is 
not necessary, ordinarily, to sweep or 
clean the surface before applying, as 
the oil incorporates with the dust 
particles, and forms a cushion over 
the hard road metal. Four or five 
applications should be made as close 
together as practicable. Between the 
latter applications, it may be found 
advisable to have men shovel the 
detritus from the sides of the road, 
filling up any small holes, and dis- 
tributing the material as evenly as 
possible. The subsequent applications 
of oil will cement this material down. 
Roads in Lincoln Park treated in 
this manner on the 19th of June, and 
having no further application of oil, 
have remained in good repair until 
the middle of October, when a lim- 
ited amount of patching was found 
necessary. A number of holes ap- 
peared in the surface, which were 
cleaned and deepened, after which a 
concrete formed of small stone 
screenings and hot mixed oils was 
filled in, and tamped down. These 
roads have given entire satisfaction, 
there being absolutely no dust visible 
during the summer months, night or 
day, and the cost did not exceed one- 
half cent per square yard for the 
five applications of emulsion put on 
in June. One or two further appli- 
cations will be necessar 5 ' to carry the 
roads through the winter. 
On several pieces of road where re- 
surfacing was necessary, the follow- 
ing method was used: The road was 
spiked by steam roller, after which 
a scarifier was used until the surface 
was forced to the proper grade. The 
emulsion was then applied until the 
road became exceedingly wet. The 
roller was then sent over the road 
until the oil and water appeared on 
the surface, when screenings were put 
on, and it was again rolled until the 
surface became dry and thoroughly 
packed. This allowed the emulsion to 
penetrate to a depth of four to five 
inches. This treatment has been 
found successful where weather con- 
ditions were good. The road must 
be allowed to harden for twenty-four 
hours before traffic is resumed over 
it, and the work should be done 
when the weather is hot and dry. 
Considerable more oil is used in this 
