June, 1920
T H E J O U R N A L O F I N D U S T R I A L A N D E A’ GIN E E R I N G C H E M I S X R Y
oil is of a specific gravity equivalent t o 5 0 degrees Baum6.” However, this is entirely unnecessary, and t h e expression, “The oil is 50 Baume gravity,” cannot be misunderstood and is entirely justifiable. I n speaking of t h e “degrees gravity’’ of an oil, t h e refiner follows t h e practice of t h e brewer who speaks of t h e “degrees of gravity in a wort,” b u t happily for t h e brewer his gravity degrees are much more easily converted into specific gravities t h a n those of t h e refiner. One meaning of t h e word gravity is “weight.” Some refiners speak of ‘(weighing” an oil, where most, meaning t h e same thing, call it “taking t h e gravity.” The word gravity has done d u t y since t h e early days for both specific gravities and for Baume degrees, a n d its use in this way is convenient. When t h e figures are attached there is little chance of misunderstanding which one is meant; b u t in t h e case of oil, t h e common expressions “higher gravity” and “lower gravity” have directly opposite meanings, depending upon whether t h e specific gravity or light Baume gravity is referred to. The first time this came t o t h e writer’s attention was when some thirty-seven years ago he heard two oil manufacturers spend much of a n afternoon talking at cross purposes, because when one spoke of a certain equipment’s giving a higher or lower gravity in t h e product, t h e speaker had in mind specific gravity, while t h e other, who was unable t o agree with t h e views expressed, understood Baume gravity t o be meant. The writer then determined t h a t t o afford himself t h e convenience of using t h e word gravity without. being misunderstood, he would say in making comparisons, “hemiei” or “lighter gravity,” which would convey t h e same meaning whether applied t o specific gravity or t o Baume degrees, and he has been trying ever since t o persuade others t o use in such cases t h e words “heavier” and “lighter” instead of “higher” and “lower,” or “lower” and “higher,” b u t with more or less lack of success. A reprehensible expression often used in oil contracts is “The oil shall be (say) 30’ gravity or better.” T h e meaning of t h e word “better” is obscure, as it depends on t h e opinion of t h e customer or a knowledge of t h e use t o which t h e oil is t o be put, t o decide whether i t would be better if i t were heavier, or better if it were lighter. T o return t o t h e subject in t h e beginning of this subhead, i t is probable t h a t if our theoretic friends wish t o do away with t h e use in t h e oil business of t h e convenient and time-honored word “gravity” as applied both t o specific gravities and Baum6 degrees, a n d t h e convenient and time-honored combination “Baumi: gravity” as applied t o t h e latter, they will have t o first kill off all t h e old-timers and then at least t h e second and third generations. A MODIFIED FORM OB THE SMITH FERMENTATION TUBE By Aubrey Vail Fuller SERVICE BIJREA_U, AMERICAN SUGAR REFINING COMPANY, NEWYORK,N. Y . Received February 16, 1920
It is frequently t h e case, especially in dealing with commercial problems, t h a t t h e analyst desires early
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information as t o t h e presence of organisms capable of causing t h e active fermentation of certain sugars. T o this end i t is t h e practice t o inoculate a fermentation tube, of either t h e Smith or Durham type, with a portion of t h e sample under examination, incubate and await developments. While, of course, this method yields satisfactory results when proper precautions regarding inoculation and incubation are observed, i t is believed t h a t , for rapidity and certainty, t h e modified construction of t h e t u b e pictured here offers certain advantages over t h e forms commonly used.
The bulb, instead of being symmetrical, is made trough shaped on its under side in order t o facilitate t h e falling of t h e growth t o t h e lowermost portion of t h e gas tube proper, with t h e results t h a t as t h e gas is liberated i t rises vertically and is trapped without an occurrence of appreciable loss through t h e bulb, as is t h e case when the Smith type is used. A very small quantity of fairly coarse acid-washed sand introduced into t h e depression aids materially in t h e disengagement of the gas as i t is formed. It has been found t h a t within a given time t h e volume of gas collected in a tube of this type is about three times as great as is t h e case when t h e Smith t y p e is used, t h e inoculum being t h e same both qualitatively and quantitatively. From this fact it follows t h a t this form of t u b e presents t h e additional advantages of enabling t h e bacteriologist t o secure evidence more quickly as t o t h e identity of t h e organism concerned by t h e customary “analysis” of t h e gas formed b y t h e soda absorption method; and, further, t h a t t h e results so obtained will be more accurate for a given period of incubation.
