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Monday, November 9, 2009

RE: BRYONET: Hoyer's Solution & chloral hydrate


Dear Des et al. The recipe for Hoyer's Solution and notes on its use
were presented by LE Anderson in Bryologist 57: 242-244 (1954).

I still use it and do not know of anything else that works as well. I
think Richard Zander has published some notes on alternative mounting
media. There are also some notes on alternatives (but one of which also
contains Chloral Hydate) in the introduction to DG Catcheside's Mosses
of South Australia.

As Cynthia Galloway correctly points out the danger with Hoyers (or
making Hoyers) is that it contains chloral hydrate. You can google a
MSDS (Material Safety Data Sheet) for chloral hydate. The Oxford Univ
MSDS gives the ORL-RAT LD50 480 mg kg-1. (ORL=Oral, RAT=rat, LD50=the
dosage that killed 50% of the rats)

So, if my arithmetic is correct, if you weigh 70 kg, you would need to
ingest 33.6 grams of choral hydrate to have a 50% probability of death
(assuming you were a rat).

According to Anderson's recipe there are 0.2 grams of chloral hydrate
per ml of Hoyer's Solution. Therefore it you imbibed c. 160 mls of
Hoyer's Soln you would have a high likelihood of not seeing the next

The Oxford MSDS recommends safety glasses and ventilation when handling
CH. It is listed as a skin, eye, and respiratory irritant. I would also
wear gloves.

I always take care when using Hoyer's, and make a point of rinsing my
hands if I contact it. But I do still use it.

Hope this helps.

Allan Fife
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  1. Is there an MSDS available for Hoyer's Solution?

    1. The danger of Hoyer's Solution is jail time if you don't have a narcotics permit (in U.S.A.). It's harmless in tiny quantities.

      R. Zander

  2. Those who avoid glycerin jelley, the best alternative to Hoyer's Solution, should try Water Glass Glycerin mountant.