NetNotes


Years ago I managed a histology core that had inherited


chemicals from other labs. Our risk management people carefully removed and disposed of the three one-pound plastic jars of pic- ric acid (still wet, but the plastic containers were deteriorating) on a weekend. I spoke about this particular incident with an elderly faculty member who had been a beachmaster with the US Ma- rines in the Pacific during WWII. He said that the torpedoes used by naval aircraſt in WWII used picric acid as the explosive (chem- ically it has some similarities with TNT) and it was notoriously unstable. He recalled a landing craſt that was shuttling a load of torpedoes from a larger ship to a captured island airbase. Te load shiſted when the landing craſt was out in the water and there was nothing leſt of the landing craſt. Histology labs use picric acid as a mordant for staining and it is an ingredient in Bouin’s fixa- tive, a favorite for investigators of ovarian tissue. Doug Cromey dcromey@arizona.edu


My high school chem lab found a dried-out jar hidden away.


Tey called the school district, who sent a person out in a rickety old truck. He put the jar in a cushioned box at the back of the truck bed and drove away taking care to go really slow over the potholes in our parking lot. Yep, ya can’t make this stuff up. Kevin McIlwrath kmcilwrath@jeol.com


Sounds like fun! We still use picric acid (“yellow fix”) as


part of the fixative mixture for some vet med biopsy preps. In an attempt to avoid environmental safety crews’ panic attacks, check for any crusty deposits on the cap area. Hopefully the chemical is in a poly bottle rather than metal and there is still liquid inside. I have stories of finding old ether cans hidden in an adobe wall of a hospital building used at one time for stor- age and converted to lab space. Ah, fun times. John Shields johnshields59@gmail.com


I have kept a 100g bottle of picric acid that I “inherited”


from a lab that moved from NYC to NJ. It could not be moved across state borders. The investigator I got it from had it for about 10 years and I’ve had it for close to 20 years. I keep it topped off with deionized water and use the saturated aque- ous solution in our primary fix according to Ito and Karnovsky (Formaldehyde-Glutaraldehyde Fixatives Containing Trinitro Compounds J Cell Biol 39 (1968) Abst.418. It really helps with membranes (I got it from an “eye” lab that studied the outer rod segments). It took a lot of careful discussions with our EHS people to finally assure them that I would ALWAYS keep it wet, wipe the lip of the jar to prevent crystal formation, etc. It is great stuff when handled with the care it demands. Lee Cohen-Gould lcgould@med.cornell.edu


Many thanks to the many people that sent helpful and informative comments. We will contact the relevant authorities (explosive experts) for the disposal of this product. Tanks again. Antonio D. Molina García antoniom@ictan.csic.es


Tis thread has been a real blast. Oops, sorry, couldn’t pass it up. Jonathan Krupp jkrupp267@gmail.com


External Light Source Confocal Listserver Hello everyone, I am having an issue with a Leica EL6000 ex- ternal light source. We use it for looking at fluorescence through the


58


eyepiece of a Quorum Wave FX Spinning Disc system. Lately, when I turn it on, the lamp stays on for about 15–20 seconds, then shuts off (the lights on the switch and shutter indicator stay on, but the mercury metal halide bulb inside shuts off). If I switch it off then back on again, the lamp turns on but then shuts off aſter a little while. When I open the lamp house, there are small white depos- its all over the bulb, notably around the connector and where the metal reflector connects to the plastic casing. I’ve removed most of it with a toothbrush and have cleaned the connectors, but the issue still persists. I was wondering if any of you might know what these deposits are, and if you think they are the cause of the issue. It could be that it is time to replace the bulb, an issue with the power supply, or something else. So, I wanted to see if anyone has any ideas that I might try before moving forward. Tank you, Mathew Duguay mathew.duguay@ladydavis.ca


How long has the lamp been used? Do users respect the


restrike/cool-down time? Is there any white deposit inside the bulb? I don’t remember which bulb the EL6000 uses, but if there’s a milky-white coating inside the discharge tube, it could be from devitrification of quartz. William Giang wgiang@pennstatehealth.psu.edu


I often see this whitish residue when changing these types


of bulbs, both with the Leica EL6000 and the various XCite lamps. I never see the residue on the actual bulb surface though. It is usually just in the bottom of the lamp house and sometimes on the base of the lamp. This is quite normal. How many hours of use has the lamp accrued? Mercury metal halide lamps should be changed at 2000 hours. The other question I have is whether the lamp is operated with a minimum run time. It is not an LED, so I recommend at least 30 minutes of use before the lamp is turned off and a 30-minute cool-down period. In fact, in our facility, we have a mandatory 1 hour on, 1 hour off rule, and if the microscope is to be used within 2 hours or less, we do not turn it off. I believe this helps with ensuring good lifetime/sta- bility for the bulb and also for safety, as it does contain mercury. Some light sources will not allow the lamp to be turned on again if it is still hot (within a certain period). The fact that the bulb is turning off might also be a problem with the power supply, or perhaps the bulb is not seated properly or it is overheating. I know it sounds basic, but I would also check that all power cords are properly inserted. Finally, if there is residue on the bulb surface, I would replace it. Although the bulbs are expen- sive, you are losing valuable time and there could be a safety issue. Jacqui Ross jacqui.ross@aucland.ac.nz


We don’t have a Leica light source but have observed


something similar with XCite and Nikon light sources. Sometimes overheating of the lamp will occur if the fan vents are obstructed. Konstantín Levitskiy microscopia-ibis@us.es


Tank you for your replies. Te bulb predates my time here


(over a year) and the screen indicating lamp use doesn’t work, so it’s impossible to know how many hours it’s been used for. I will check things that some of you have mentioned, as well as replace the bulb if the rest seems fine (rather than retire it completely). Mathew Duguay mathew.duguay@ladydavis.ca


Given the unknown number of hours of use, I would replace


the bulb. I use a mini-vacuum cleaner to clean out the lamp house when I change the bulb. Jacqui Ross jacqui.ross@aucland.ac.nz


www.microscopy-today.com • 2022 July


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