"Some people," grumbled Gus Wilson,
"sure do waste a lot of time finding out what they want to know."
The veteran auto mechanic disgustedly
shoved the telephone away from him.
Joe Clark, his partner, who had called
him into the office of the Model Garage to answer the phone, grinned
sympathetically. "What did that bozo want?' he inquired. "If I'd known he
only wanted to ask a bunch of fool questions. I wouldn't have bothered
"Funny you didn't recognize him,"
replied Gus. "That was old Dexter, the bird who's always spouting
theoretical stuff about calories, thermo-something, or other, and the rest
of it. He'd rather mess around for hours with a pencil trying to figure out
something than to ask someone who knows."
"Then what's he pestering you for?"
Jose asked. "Why don't he figure it out if he's such a shark at it?"
"He didn't ask any questions," grunted
Gus. "He says he's coming here to get me to help him on some of his blasted
calculations. I didn't get what he was driving at except it had something
to do with specific gravity. I just told him to come ahead and I guess he's
on his way now."
A few minutes later Dexter drove up
and insisted on bringing his car inside instead of parking it in front of
the garage. It was below freezing outside he explained and he was afraid
the radiator might freeze.
"I am sorry to bother you, Mr.
Wilson," he said, as he reached into his car and dragged out several thick
and musty looking scientific books. "It is just a relatively simple problem
in specific gravity. That is, it should be simple enough, but there are
several confusing factors that complicate matters."
"What are you trying to do, figure out
what makes ice float?" smiled Gus.
"No," replied the other. "You
recommended that I use glycerin in the radiator this winter and I took your
advice. The results have been excellent until day before yesterday, and
then I unfortunately forgot to open the radiator shutter until the motor
became so overheated it began to boil, and I am afraid that a large part of
the solution squirted out the overflow pipe with the steam. Now I don't
know what actually is left in the radiator. I looked up the specific
gravity of glycerin and found it was 1.265 degrees at ordinary
temperatures. It occurred to me to calculate the specific gravity of the
mixture I was using and then by test see what I actually had. But these
books show that it is rather complicated."
"Bumped right into a tough one, didn't
you?" said Gus. "Seems to me I remember reading some place that 'a solution
is a uniform mixture that doesn't follow the law of definite proportions.'
That floored you, eh?"
"That's it precisely," said Dexter,"
and now I am unable to find a formula to fit the case. Perhaps you can help
me?" "Sure," Gus replied. "Chuck those blame books back in the car. We
won't need 'em. Hey, Bill" he called to the youngster who was sweeping the
other side of the garage. "Chase yourself down to the drug store and buy me
a couple of ounces of glycerin and a test tube. Make it snappy!"
"Now," Gus explained when Bill
returned a few minutes later, "all we've got to do is to take the hydrometer
float out of this storage battery hydrometer and see how it floats in
different mixtures of glycerin and water. What's the matter with that way
of finding out what you want to know?"
"But will the results be sufficiently
accurate?" Dexter objected doubtfully.
"Why not?" countered Gus. "You could
wear out a couple of pencils figuring it closer than the paper on the wall,
and even then you wouldn't be dead sure.
These cheap hydrometers are no great
shucks for accuracy. Your figures might be all right and a bum hydrometer
would throw you way off. But if you make up the actual mixtures and float a
hydrometer in 'em - any old hydrometer - you can keep that hydrometer just
for testing your radiator solution, can't you?"
"You've proved your case," admitted
"These, storage battery hydrometers,"
Gus continued, "don't read much below 1.075, so you won't be able to tell
anything about very weak solutions of glycerin and water. Let's start with
one part glycerin to two parts water. That's a thirty three percent
"Reads about 1.080," said Dexter,
bending over to get his eye on a level with the top of the solution in the
"Paste that in your hat," Gus
suggested. "A glycerin solution that floats this particular hydrometer at
1.080 will keep Jack Frost out of your radiator down to almost ten degrees."
"But we occasionally have colder
weather than that in this latitude," Dexter objected.
"Sometimes," agreed Gus, "let's see
how it reads in a forty percent solution. That won't freeze down to zero.
And if we add one third of a part more glycerin to what we've got in the
test tube already we'll have mighty close to a forty percent solution."
Dexter did a bit of figuring while Gus
was stirring in the added glycerin and found that the auto mechanic was
"There you are," said Gus, as he
jiggled the test tube to make the hydrometer float without sticking to the
glass walls. "Just 1.100 on the scale. Nice easy figures to remember.
Keep the solution at 1.100 if you want zero protection."
"Excellent!" Dexter exclaimed. "Now I
have merely to insert the hydrometer in the radiator at any time to
determine the strength of the solution."
"Not any time," answered Gus. "You
forget that a hot solution is expanded and the hydrometer will sink down
below where it ought to float. That reading is only good at about sixty
"Would that reading also apply to that
new antifreeze, ethylene glycol?" Dexter asked.
"I should say not!" replied Gus
emphatically. "It's good only for a mixture of glycerin and water.
Ethylene glycol is just as good as glycerin as an antifreeze, but the pure
stuff reads only 1.120, so you'll have to use a hydrometer that reads lower
than the storage battery hydrometer to test it when it's thinned with
water. Plain water reads 1.000 on the hydrometer scale, you know.
"And if it's alcohol you're trying to
test, you'll have to have a hydrometer that reads even below that, because
alcohol is lighter than water."
"If glycerin and ethylene glycol do
not evaporate as does alcohol, I suppose there's no necessity for testing
quite frequently as is the case if you are using alcohol," Dexter observed.
"Depends a lot on how hot your motor
runs, "Gus explained. "If you don't go spraying the road with expensive
cooling solution through a leak, or by boiling it over as you did, and the
motor doesn't run so hot that it evaporate a lot of water, you can just
squint in the radiator once in a while to make sure that the solution is
"Either glycerin or ethylene glycol
will last almost forever if you don't lose 'em through leaks.
There's no reason in the world why you
shouldn't use the same solution winter after winter, adding a little
antifreeze each year to make up for leaks if the hydrometer tells you it's