Equipping A Laboratory: Part III
Special Glassware and Some Other Apparatus 

by Richard L Howey

 
 
 

In the previous part, I discussed some basic types of glassware that almost anyone will need in his or her laboratory. In this segment I am going to discuss two types of items: 1) some special glassware (although some of it's plastic) that has a somewhat specialized application or may be quite handy, but is not essential and 2) fairly basic types of apparatus which the more advanced amateur may wish to acquire.

Section 1: Dehydrating or Staining Jars.—If you are staining smears, protozoan or algal preparations, or sections of botanical or animal tissues, then you will very likely want some Coplin staining jars. These have slots on two sides to keep the slide surfaces separate and you can place six slides in at 1 per slot or you can double that by placing two slides back to back in each slot. You fill the jar with the stain or reagent and place your slides in the slots which allows you an opportunity to carry out timed studies to find the optimal duration for a particular stain or reagent on a particular type of specimen. A drawback: While with most stains, one can re-use them and process a large number of slides over a considerable period of time before having to replace the staining solution, nonetheless, the jars do require considerable quantities of fluid. Ideally, one would have a separate jar for each stain and reagent. In practice that's not feasible unless you have a large research grant.

If you are preparing specimens for permanent mounts, then you will probably want 10 or so such jars to accommodate the various concentrations of alcohol, the stains, xylene, and possibly cedar oil. These procedures are complex enough and sufficiently time-consuming that if you are going to utilize them very often, there is certainly justification for such an acquisition. Glass Coplin jars are not inexpensive, but now you can obtain heavy-duty plastic ones which are quite serviceable and considerably cheaper.

Many professional microscopists would recommend a different sort of jar, one which is designed for cover glasses rather than slides. They insist that the best preparations must be made on the cover glass rather than the slide and there are good arguments for their position.
 
 

Section 2: Funnels.—I didn't mention funnels in the previous installment on basic glassware, because glass funnels break rather easily and are hard to clean. You can get various plastic laboratory funnels from a supply house, but it's generally cheaper to go to your local discount store and buy several sizes.

There are many kinds of specialized funnels and two are worth considering here. There are high speed filter funnels which have spiral grooves in the inside thus significantly speeding up the filtering process. Why is this important? Consider two examples: 1) if you are filtering a solution in a volatile solvent, such as a stain in alcohol, then you want to minimize the filtration time to avoid evaporation of the solvent which would effect the concentration of the solution or 2) if you are filtering to concentrate organisms for examination, you will again want to minimize filtration time to avoid the possibility of losing some of the organisms on the upper parts of the filter paper as a consequence of partial drying. This type of funnel is available from $1.90 to $9.70 depending upon size.

The other type to consider is also a filter funnel, the Buchner funnel. This has the advantage of allowing you to place a piece of filter paper flat at the bottom of the funnel, thus avoiding the three layers of paper on one side and one on the other when the paper is folded to fit the traditional funnel. Plastic Buchner funnels can be obtained from $3.45 to $14.00 depending on the filter paper size which ranges from 4.25 cm. To 11.0 cm.
 
 

Section 3: Odds and Ends—

1) Wash bottles—These are very convenient for directing a stream of fluid into a tube or dish. They come in a variety of sizes ranging from 12.5 ml. To 1000 ml. I find the 250 ml. to be the most useful size for my purposes. There are specially labeled wash bottles that manufacturers claim are leak proof and can be used for solvents, such as, acetone, methanol, and toluene. Personally, I remain skeptical. This seems to be a way to waste a fair amount of expensive solvents and inhale some nasty fumes in the process, so, I use mine only for distilled water, artesian water, pondwater, different kinds of culture media salt solutions, and the weaker alcohols where evaporation is not so crucial.

2) Mortars and Pestles—These are used for reducing materials to a powder. I prefer glass ones over the porcelain as the latter are not always evenly glazed or over time will develop small chips in the surface. Chemicals can lodge in these areas and contaminate other preparations. Furthermore, the glass ones are easier to clean.

3) Thermometers—To paraphrase Gertrude Stein: "A thermometer is a thermometer is a thermometer." Well, yes and no. There are partial immersion and total immersion thermometers, red alcohol-filled thermometers, mercury thermometers, digital thermometers and electronic digital thermometers with a timer and alarm and a switch to allow you to measure the ambient air temperature or the temperature of a solution by switching over to an attached probe. A good partial immersion alcohol thermometer is quite suitable for most purposes (mercury spills are messy to deal with and potentially dangerous). Oh, yes, I forgot to mention that you can get them in Centigrade, Fahrenheit, or both. In dealing with micro-organisms, it is often important to keep a record of temperature to get an indication of the ranges at which some species thrive and others languish. I bought a packet of 10 "economy" thermometers which are mounted on plastic (for only $7.50) and take a couple with me when I go collecting to measure the water temperature at the site. If you lose one of them (at 75 cents), you can survive, but I wouldn't want to lose a moderately expensive digital thermometer at pondside.

4) pH Meters and Papers—Monitoring the pH (hydrogen ion concentration) will help you in maintaining sensitive micro-organisms in culture. Many organisms have fairly stringent pH requirements. A sample taken from a cold lake and then brought into the lab will warm significantly and this can alter the pH. As the culture develops over the hours and days, oxygen will be consumed and there will be an accumulation of waste by-products. Both of these factors will gradually alter the pH, so you may wish to measure the pH and then adjust it to an optimal state by the use of buffers. Papers for measuring pH come in several types; wide range types can measure from 1-12 or even 0-14, whereas short range papers can be selected for a particular range which is relatively narrow. For example, you can select a paper that will measure from 6.0 to 8.0 in 0.5 increments. The strips or rolls of the paper come with a color chart and after you thoroughly wet a portion of the paper with the solution you are testing, you can match its color with the chart to determine the pH. For many general applications, these papers are perfectly suitable.

If you require greater accuracy, then you might wish to consider the purchase of a pH meter. It used to be that benchtop meters were the answer, but they cost several hundred dollars. Now, however, with micro—miniaturization, the use of digital displays and tiny batteries, one can purchase a hand-held meter with probe which can measure 0.01 pH with plus or minus 0.2 pH accuracy for $32.95—a very good investment for the amateur microscopist.

If you get interested in the chemistry of the water of your samples, there are test papers and meters to measure everything from Ammonia to Zinc and some very interesting studies can be carried out investigating the effect of the presence or absence as well as the concentrations of specific ions on the growth and behavior of particular organisms. For example, some ciliates, Lacrymaria olor being one, have a high tolerance for both magnesium and sulfate ions and yet for other aquatic organisms, magnesium sulfate is a quite effective anesthetic. Research has also shown that in some ciliates the sodium/potassium balance can affect locomotion. Some very intriguing experiments have been done using the large band-shaped ciliate Spirostomum, in which a detergent was used to wash the protoplasm out of the pellicle or cell envelope, leaving a dead model with a pellicle, kinetosomes, and cilia more or less intact. By increasing the concentration of potassium ions, this dead model can be induced to swim—backwards! So the chemistry of the environment can pose many fascinating problems to investigate.

5) Hotplates and Stirrers—If you are going to buy a laboratory hotplate, be sure to get one with a variable temperature control. A popular "student" model (what does this mean!?!) has a thermostat preset for 399 degrees Centigrade for $95.00! The nice thing is that it has a flat stainless steel top, but for only $25.95, you can get a hotplate with a coil top and a temperature control.

What would you want with a stirrer? Some compounds are notoriously difficult to dissolve and a magnetic stirrer, while not essential, is a neat gizmo to have (the microscopists and their toys!) A stirrer uses a coated (preferably with Telfon) magnetic bar which is placed in a beaker or flask with the solution you wish to stir. The base generates a field which spins the magnet, thus stirring the solution. You can purchase an inexpensive model in the range of 100 rpm-1,000 rpm for $75.95. A luxury for most amateurs, but if you are doing lots of agar preparations, it is very useful.

You can also buy combination hotplates and stirrers, but these are beyond the price range of most amateurs—the lower line being $300-$400.

6) Balances—For the beginner, it is generally best to have solutions made up by a pharmacy or supply house. However, over a period of time, you may accumulate a fair number of chemicals and stains and eventually want to make up your own solutions and for this you will need a balance. You can purchase a balance that will weigh to 0.0001 gm., but it will cost you a minimum of $1,400.—However, now that you have regained consciousness, I'll tell you that a balance which weighs to 0.01 gm. is almost always adequate for the amateur and has a price range from $128 for one with a single pan and three beams with sliding weights to $190 for a small electronic balance with digital readout. A balance is an investment and given proper care, it should last a very long time. CAUTION: When weighing chemicals, always exercise great care. Avoid skin contact and especially contact with the eyes or mucous membranes. Be careful not to inhale any of the dust or vapors. Know in advance what procedures you need to carry out if you do happen to have a spill.

7) Waterbaths—A waterbath can be very useful if you are doing a lot of slide preparations using glycerine jelly as a mountant or if you are regularly using agar as a growth medium or for heating certain chemicals that should not be heated directly in a tube, flask, or beaker over a flame. For some reason, water baths are inordinately expensive and the cheapest one I have seen advertised is $269! Too much, I say, too much!

Fortunately, there are a couple of easy and inexpensive alternatives. If you bought a hotplate with a variable temperature control, put some water in a beaker, set it on a low temperature setting and place your tubes of agar or your (heat resistant) jar of glycerine jelly in the water and you're in business. If you decided not to buy a hotplate, but still need a water bath, then you can go to a discount store and buy a small electric soup warmer with a temperature control and use it in the same manner and at a cost of only about $20.

8) Hand Microtomes—Microtomy is a science (and art) all in itself and is best left to professionals and gifted amateur specialists and I fit neither of those categories. However, a hand microtome to make some reasonably tiny sections can be a useful tool and one can learn a great deal from the process of cutting such sections. Rotary and sliding microtomes are very expensive ranging from many hundreds of dollars to thousands. Rocking microtomes can sometimes be obtained at a reasonable price, however, I would recommend that most amateurs stick with a hand microtome. The large microtomes have heavy, razor sharp blades. If one is dropped, NEVER try to catch it—in fact, one should train oneself to step back away from the area. Attempts to catch microtome blades have resulted in the loss of fingers and caused other forms of severe damage to the hands.

With a hand microtome, a sectioning razor or a surgical scalpel can be used. This type of microtome comes in several styles and the handiest is one which clamps onto your laboratory table. These also are not inexpensive, but recently such a version, which is made in India, has appeared on the market for $60 to $80. Many older books on microtechnique suggest surrounding the specimen with elder pith to support it while it is being cut. This is not a commodity readily obtained, at least not in this country—so what does one use instead? Carrots! Fresh, crisp, crunchy carrots. You can cut pieces by hand or you can invest $20 in a set of cork borers and do a rather more elegant job. Measure the inside diameter of the microtome well (mine's 18 mm.) and find the cork borer closest to that size and cut a plug out of the carrot. If you are sectioning a thin leaf, you can simple split the carrot core down the middle and put the leaf between the two pieces and pack the whole thing into the well. If, however, you want to section a stem of a plant, then you can select one of the smaller cork borers and cut a section out of the center of the carrot core and then slice it in half. In this way, you don't crush a delicate leaf stem between two flat surfaces.

Clearly using these simple tools, you are not going to be able to produce ultra-thin sections, but with a bit of patience and practice, you can produce some very satisfactory sections and have the pleasure of examining material which you yourself have prepared.

9) Centrifuges—A centrifuge is, for most amateurs, an indulgence. The cheapest one that accommodates standard centrifuge tubes costs $265 and many benchtop models cost thousands of dollars. So why do I have a large benchtop centrifuge? Well, some years ago when the molecular biology department moved into a new building, they sold off a lot of old "obsolete" equipment and so I got this large, heavy, perfectly functional centrifuge for $25. I couldn't resist.

Universities, research institutes, corporations, and hospitals can all be sources for used laboratory equipment at very reasonable prices. However, it's important to do your homework and to check out any equipment you are thinking of buying. An expensive centrifuge for $25 is no bargain if the motor is burned out. I insist on testing the equipment before buying it and my centrifuge was indeed a bargain.

Oh, yes, why would an amateur microscopist want a centrifuge in the first place? Well, it's a wonderfully efficient way of concentrating organisms which you wish to study. Rather than taking a drop of water from a pond sample hoping to find an interesting variety of organisms, you can take 15 ml. of the sample, spin it, pipet off the excess liquid and then take a drop of concentrated sample for examination under the microscope. Interestingly, with some of the larger ciliates, the whirling seems to act as a temporary anesthetic. When using a centrifuge, you must always make sure that it is balanced by putting the same level of fluid in each tube. If you have empty tubes, it throws off the balance and can damage the instrument.

The inevitable risk of being a passionate microscopist is that you begin rather quickly to accumulate specimens, apparatus, glassware, and assorted equipment and there comes a point when you sit back and wonder how all of this happened. You also may discover that there are a significant number of items for which you no longer have a use or the space to store them. Some of the items you may wish to sell and you can advertise them on Microscopy-UK Sales and Wants, but other less expensive items can be donated to microscopists who are just starting out or to an amateur microscopical or natural history club to help continue the tradition.

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ENDNOTE

Prices are once again taken from the 2000-2001 Cynmar Scientific Equipment Catalog. For additional information, see the endnote in Part I of this series.

Comments to the author Comments to the author sent via our contacts page quoting page url plus : ('rhowey','')">Richard Howey welcomed.
 

Earlier articles by the author in this series:

Part I Dissecting tools.

Part II Glassware and related accessories.

The author's other articles on-line, can be found by typing 'Howey' in the search engine of the Article Library, link below.

Related articles

Rosemarie Arbur describes an easy to make hand-operated centrifuge in this Micscape article.


 
 

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