I think i t was in 1910 that I wrote to a maker of chemical apparatus asking him why he marked all of the measuring instruments in ml. rather than cc. He replied "Ask the Bureau of Standards." I wrote a letter to Dr. Stratton, who was then Chief of the Bureau of Standards, and he replied very positively that the liter was not properly defined as one thousand cubic centimeters and that the milliliter was the proper term for one-thousandth of a liter. He informed me of the fact that the emor was 0.03 of one per cent and to this I replied that I had read about the error but had no idea it was so slight. I told him that I thought it was very silly to insist upon the distinction. However, no one to whom I talked failed to agree with the logic of Dr. Stratton's remarks. Since that time I have never seen a new measuring instrument that was not marked in ml. rather than cc.

Unfortunately, chemists had for quite a number of years been using the Mohr liter which was the volume occupied by a kilogram of water a t 17.5'C. More- over, Wagner thought that this temperature was too far below the average laboratory temperature and he proposed the temperature of 20°, which is the tempera- ture a t which measuring instruments are today assumed to be correct. Others preferred to use true liters as defined by our Bureau of Standards. When the Bureau of Standards asked the makers of measuring instruments to use ml. rather than cc., there were a t least three different kinds of liters in fairly common use-the true liter, the Mohr liter, and the Wagner liter; and there were three different abbreviations used for the thousandth part of the liter, namely, c.c., cc., and ~ r n . ~ The error between the cubic centi- meter and the milliliter is least with the true liter. I am certain that the Bureau of Standards thought they were making things simpler and better by asking in- strument makers to calibrate their instruments in terms of the true liter and to use the abbreviation ml. rather than c.c., cc., 01 c m 3

A few years ago, the leading English journal on analytical chemistry, The Analyst, instructed all per- sons submitting papers to use the abbreviation ml. un- less they actually meant a cubic centimeter.

The prefix milli is commonly used to represent one- thousandth of the whole. Thus we have milligram, millimicron, millifold, millifarad, milligrade, millistere, milli-equivalent, etc., and these terms are not difficult to understand. The idea that the six syllables of cubic centimeter can be pronounced more quickly and with less use of the tongue than the four syllables of nzilliliter is interesting, but not true. The idea that cc. can be written more quickly and easily than ml. is certainly true in the case of the amateur typist who rarely uses more than two fingers in his typewriting but of no other typist and certainly the reverse is true in writing longhand.

There is a tremendous amount of inertia against doing anything differently from that done by our fore- fathers. Thus scientists for about one hundred and fifty years have been telling folks that the metric

system is better than the English system of weights and measures hut, except in times of war when we have to make ammunition and machines to correspond to those made with the metric system, progress toward making its adoption universal is very slow. Our textbooks, particularly those for beginners, are tenihly conservative and the authors explain things the way they were taught irrespective of any results ,of modem investigations. Thus youth is still being taught that sodium is first set free when a solution of sodium chlo- ride is electrolyzed although M. Le Blanc in about 1890 showed that such an idea is preposterous; youth is still being taught that the electric current flows in a north to south direction although most every scientist knows that the electric current is really a stream of electrons flowing in a south to north direction, and, as a result of the same sort of conservatism, many texts still teach that a liter is one thousand cubic centimeters.

It has been over forty years since I began to say milliliter instead of cubic centimeter, and I have cer- tainly taught thousands of students to do the same thing. As far as I know, none has offered any argu- ment against this practice. It is true to be sure that in 1910 the United States Pharmucofileia adopted the abbreviation mil. instead of cc. and this caused so much confusion and provoked so much opposition that the editors never have dared to use anything but cc. in subsequent editions.

WILLIAM T. HALL Rowr~s~en, MASSACHUSETTS

Ultraviolet Tyndallorneter

To the Editor: Your articles are always a source of interest to me,

but one in the February, 1943, issue has especially at- tracted my attention. I t is entitled "A simple and permanent tyndall cone apparatus," by Abrahams and Dubner.

You will be interested to know that this instrument can also be employed as an "Ultraviolet Tyndallome- ter," and the effects produced with it used for a wide variety of purposes as well as for spectacular lecture demonstrations. The ultraviolet Tyndallometer is an instrument of my origination, being first described in detail in the hook "Ultraviolet Light and Its Applica- tions."

The Abrahams and Dubner apparatus can be used without modification, except that a small amount of visible light fluorescing substance is added to the solution to enhance the features of the cone. Beta- methyl umbelliferone is very satisfactory in this regard. However, by substituting an ultraviolet source for the small light globe, and a quartz or pyrex lens for the glass lens, it is possible to construct a simple ultraviolet Tyndallometer which will show properties of a solu- tion such as its absorption characteristics, the Tyndall effect, and qualities in regard to fluorescence intensity.

JACK DE MENT Coucn BUILDING

PORTLAND. OREGON