Liquid Measurements Guide

Liquid Measurements in the Lab

Introduction

Converting between different liquid measurements correctly is vital to success in any scientific exploration and experiment. It goes without saying that scientists are dealing with minutiae on a constant basis; one momentary slip such as an erroneous liquid measurement conversion can totally distort an experiment's processes and results, and render the findings useless.

Needless to say, this is especially important for agricultural experiments and investigations, which rely squarely on precise measurements of water and liquid ratios to come out with useful information.

Liquid Measurements in Beaker (Blue Liquid)

Fluid Ounce Measurements

It may surprise you how many mistakes investigators make when doing conversions, but many times these are graduate students who may not have yet become as disciplined about not being careless than more experienced scientists--even though the latter can also make mistakes in conversions, since they, too, are human, all too human.

What is most important of all to get accurate for agricultural investigations are "fluid ounce" measurements. These just so happen to be the class of liquid measurements that seem most confusing to people, as well.

So, let's get fluid ounce conversions straight. (The fluid ounce, by the way, is defined as a unit of volume or capacity in the U.S. Customary System that equals 29.57 milliliters or 1.804 cubic inches). An ounce of weight is NOT a fluid ounce, either.

1 teaspoon = 1/6 FL OZ.

1 tablespoon = 1/2 FL OZ.

1 fluid ounce = 1 FL OZ.

1 gill = 4 FL OZ.

1 cup = 8 FL OZ.

1 pint = 16 FL OZ.

1 quart = 32 FL OZ.

1 gallon = 128 FL OZ.

1 firkin = 1152 FL OZ.

1 hogshead = 8064 FL OZ.

More Liquid Measurement Apparatus

Liquid and Dry Measurements

It is also vitally important in these kinds of endeavors to be able to convert accurately between dry measurement and liquid measurement, especially when dealing with chemical solutions or the saturation of soil.

1 dry pint = 1.1636 liquid pints

1 dry quart = 1.1636 liquid quarts

1 dry gallon = 1.1636 liquid gallons

Parallax Error in Liquid Measurements

Parallax Error

There are also two more important possible components of doing liquid measurements that I'll briefly mention.

The first is "parallax error". This can be a problem when viewing liquids contained within such things as graduated cylinders. The Sci-Tech Dictionary defines "parallax error as an "error in reading an instrument employing a scale and pointer because the observer's eye and pointer are not in a line perpendicular to the plane of the scale." This is the reason why, for instance, chemists insist on only determining the amount of a liquid contained in a graduated container by looking at it from a perfectly horizontal, aligned viewpoint, and then only after the liquid within the container is completely still (i.e., no longer oscillating or creating waves due to the container being moved).

Liquid Measurements in the Real World (For Pest Control)

The Aliquot Method

I also wish to mention along these lines the LIQUID ALIQUOT METHOD. In this measurement technique, which is similar to titration, a weighable quantity ("aliquot") of a condensed substance is dissolved in a calculated volume of a suitable solvent such as water. Next, an aliquot of the solution which contains the desired amount of that condensed substance is removed. The total volume of solution as well as the aliquot volume should now be such that they are easily and accurately measured; the most desirable gradations are whole number multiples of 5 ml.

Clearly the Liquid Aliquot method is highly useful when doing investigations into agricultural fertilization or pest control methods.