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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
		Rob Gardner, Digest Coordinator


Contents:
  Homebrew Digest #249 (September 10, 1989)
  doubts about SG temp corrections (Dick Dunn)
  "How not to open a beer" (Alex M. Stein)
  CASEY at MIT.MFENET (CASEY)


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HOMEBREW Digest #249		             Sun 10 September 1989


	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
		Rob Gardner, Digest Coordinator


Contents:
  doubts about SG temp corrections (Dick Dunn)


Send submissions to homebrew%hpfcmr at hplabs.hp.com
Send requests to homebrew-request%hpfcmr at hplabs.hp.com

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Date: 9 Sep 89 01:04:58 MDT (Sat)
From: hplabs!gatech!raven!rcd (Dick Dunn)
Subject: doubts about SG temp corrections

I've been watching the discussion of temperature corrections for hydrometer
readings for a while.  I guess it's time to toss in my twopence.

A quick check in the Rubber Bible seems to indicate that the temperature
coefficient of expansion of water over some interesting range (say 50-100
F), while not linear, is not warped enough to give you as much as a point
of error relative to a 60 F reference.  So that's cool...however:
	- How does the expansion change with sugar in the water?  There
	  are two questions here.  First, how much does the coefficient
	  change--that is, do you have to apply a significantly different
	  temperature correction factor depending on the gravity? Second,
	  does it get more or less linear than the expansion of water?
	- What about the expansion of the glass in the hydrometer itself?
	  Is this really negligible?

I've always gone by the (safe, but perhaps overly conservative) rule that
you shouldn't try apply temperature corrections outside the range of per-
haps 50-75 F.  This seems like a good idea given the potential for non-
linearity in expansion coefficients, difficulty in getting temperature
measurements right, tendency to warm/cool while you take the measurement,
etc.

One other note-in-passing:  Somewhere there was a discussion of the "poten-
tial alcohol" scales on hydrometers.  I have two hydrometers.  Both show
potential alcohol, and both clearly say "by volume", but they're not the
same.  However, the one that's different (:-) has the zero for potential
alcohol at a gravity value other than 1.000.  Is this just a simple
screwup, or does someone know a reason this might make some sense?  Seems
wrong to me...I'd expect water to have SG of 1 and potential alcohol of 0.
---
Dick Dunn	{ncar;ico;stcvax}!raven!rcd		(303)494-0965
			or	rcd at raven.uucp

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End of HOMEBREW Digest #249, 09/10/89
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Date: Wed, 6 Sep 89 14:18:01 PDT
From: rutgers!retix.retix.com!alexs at hplabs.HP.COM (Alex M. Stein)
Subject: "How not to open a beer"


Reprinted from Chemical & Engineering News:

"A weird encounter with a non-screw-on beer-bottle cap was
reported recently by physician Karanvir Prakash and colleagues at
Bronx-Lebanon Hospital Center, Bronx, N.Y.

"The subject, a man aged 36, was `watching a tense baseball game
on a hot summer afternoon.'  He was opening a bottle of beer with
his teeth when the compressed gas inside blew the loosened cap
down his throat.  Off to the emergency room.  The cap had to be
removed surgically because its serrations were `firmly embedded'
in mucous membrane.  The physicians' report of the episode
describes the cap carefully as `measuring 2.7 cm in diameter and
bearing the words MILLER HIGH LIFE.'  The patient came out okay.

"The episode `highlights the hazard of opening bottles of
carbonated drinks with the teeth,` say Prakash, et al.  They
suggest that such drinks be marketed only in cans.  You could cut
your fingers, but that would appear to be preferable to a bottle
cap in the throat."

Alex Stein
alexs at retix.com

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Date: 	  Sun, 10 Sep 89 21:07:46 PDT
From: CASEY%MIT.MFENET at CCC.NMFECC.GOV
Subject:   CASEY at MIT.MFENET

subject:  amateur yeast experiment:

I started brewing only four months ago, and am still in the wild experimentation
stage.  I quickly became confused about different brands of yeast available,
and was able to get almost no reliable information, so I tried an experiment.
The results are posted below.  I just joined this bboard, so I have no idea if
this sort of thing is common.  I'd love to hear of other experience or comments
along the same line.  If this is an old subject, just flame to me directly
instead of clogging up the board. 

First:  I already realize that I used a pretty bad recipe for the test.  It
had far too much bittering hops for balance.  The idea was to look for 
differences in yeasts, however, so I tried to look through it. I was also
experimenting on yeasts suitable for my conditions (Boston in summertime),
where the temperatures are ungodly hot, and mold runs rampant.  I also realize
the problem with my lack of gravity measurements and exact temperatures, sorry.
Don't chew me out for these, but I would be interested to hear if one of the
"bad" yeasts might be perfectly good under other circumstances. 

7 gallon recipe:
2x 3.3# can M&F light unhopped
.75# M&F light unhopped spray
.75# crystal (steeped while coming to boil)
1 tsp gypsum
2oz clusters boiling
.5 oz cascades finishing
Divided evenly into seven 1 gal bottles, different yeast in each bottle.
Fermented at about 75-85 F.

Results were:
1st:       Edme ale - best overall.   rounded, slightly sweet.  some diacetyl.
                 nice balance.  fermented rather slowly (3-4 days).
2nd/3rd:   Whitbread ale - lighter, crisp.  poorer head.  some esters.
                 very fast fermentation.
2nd/3rd:   CWE ale - slight yeasty bite.  very dry (attenuative).  good head.
                 no esters.  extremely fast fermentation (frighteningly).

... these three were all quite good, and I have been using them successfully
since then.  they all rated fairly close together.  the remaining four were
all quite a bit worse (a very big gap in quality), and I haven't touched them
since.  none seemed to have spoiled, they just had unforgiveable ester 
content and/or carbonation qualities.  (this could be due to temperature).

4th:       M&F ale - heavy yeast bite.  flat head.  very little ester taste.
5th:       Kitzengen lager - (fermented warm) this had the best head and
                 carbonation quality.  very dry (attenuative).  extremely
                 bad ester content.
6th:       Doric ale - yeast bite.  very estery.  bad head.  overall horrible.
7th:       Red Star ale - same as Doric, but a little worse.

these were the results of two different double blind tests, with only minor 
variations between the two events.  I might try this sort of thing again
with a better recipe after it cools down, and include some liquid cultures
that I've tried since (with luck); unless somebody else out there has 
done it for me and can post the results.  I have heard that the next issue of
Zymurgy will cover yeasts - perhaps all this will be superceeded soon.
                          Jeff Casey   CASEY%MIT.MFENET at CCC.NMFECC.GOV

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End of HOMEBREW Digest #250, 09/11/89
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