Re: Snow in South Carolina, was Re: precipitation of dichromates

Hi Gord, here on the West Coast- BC we only had 2
feet of snow in mid-Jan. The problem is; noone knows to slow down! We all
had fun and did some skiing and of; course photographed. Susan.
----- Original Message -----
From: "Gordon J. Holtslander" <holtsg@duke.usask.ca>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, February 26, 2004 10:10 AM
Subject: Re: Snow in South Carolina, was Re: precipitation of dichromates

>
> Last month, January 29 Saskatchewan was the coldest place on earth at
> -52.3 C (thats -62 F) it felt a little colder, there was a wind. - I think
> it also snowed :)
>
> What did we do? We went to work and the kids had school.
>
> Maybe when it gets above freezing everything will shut down. We might all
> forget to take off our overcoats and suffer from heat exhaustion.
>
> Gord
>
> Small Saskatchewan community the coldest place on Earth yesterday at
> -52.3C
>
> Key Lake, Sask., was the coldest place on the planet yesterday, with a
> temperature reading that dipped to -52.3C, not including the windchill,
> according to Environment Canada's experts on ice and...
> Source: CanWest News Service
>
> On Thu, 26 Feb 2004, Sandy King wrote:
>
> > Chris,
> >
> > When it snows in South Carolina, even an inch or so, school is
> > cancelled, regardless of what the administrations says or does!! It
> > is called self-cancel, carried out by the students with a compliant
> > faculty. Seriously, no way I am going to leave the comfort and safety
> > of up home and venture out on the roads around here when there is
> > snow. That would be like playing demolition derby.
> >
> > But the great thing about snow here is that it goes away quickly. The
> > forecast is calling for up to eight inches or more of snow here today
> > and tonight, but up to the high 60s by the weekend.
> >
> > Now forgot about your classes and pretend that you are Ansel in
Yosemite.
> >
> > Sandy
> >
> >
> >
> >
> >
> > >Thanks, Marek.
> > >
> > >Why would pot di be insoluble in alcohol and am di not? If this is too
> > >complex an answer, don't bother...I'm just interested.
> > >
> > >In the old BJPs it was talking about the two at a time when pot di was
the
> > >norm, and how pot di, because it is so low in saturation compared to am
di
> > >(10 vs 30%), with a drop in room temp you tend to get crystallization
around
> > >the bottle stopper all the time. That's always plagued me, too, in a
> > >inconsequential but messy way with using saturated solutions, so I
thought
> > >that'd be another goood reason to use am di at lower than saturation
point.
> > >And then I came across this alcohol statement and was wondering.
> > >
> > >Can't believe it--it is SNOWING here in SC. Looks like MT
outside....I'm
> > >waiting to see if school is cancelled. In MT it'd have to be 2 feet of
snow
> > >and 30 below zero before they'd consider closing anything.
> > >Chris
> > >----- Original Message -----
> > >From: <mmatusz@pdq.net>
> > >To: <alt-photo-process-l@sask.usask.ca>
> > >Sent: Tuesday, February 24, 2004 1:36 PM
> > >Subject: Re: precipitation of dichromates
> > >
> > >
> > >> Chris,
> > >> Potassium dichromate is insoluble in alcohol, ammonium dichromate is
> > >> soluble, although I do not have the exact solubility numbers. You
gum
> > >> solution is mostly water anyway. If you like to print with
concentrated
> > >> dicromate solutions (around 15% in the final solution or even
higher)then
> > >> it is likely that you can not add a lot of alcohol, or else
potassium
> > >> dichromate will precipiate. Again the alcohol addition is also
small,
> > >> maybe 5%. If you are printing with a dilute dichromte solution you
might
> > >> not have a problem with potasssium dichromate and alcohol. This is
one of
> > >> those things that it is so much easier to test in practice anyway.
> > >> Happy printing
> > >> Marek Matusz, Houston
> > >>
> > >> > Do any of you chemists out there know why potassium dichromate
would
> > >> > precipitate out of solution when alcohol is added vs. ammonium
> > >dichromate
> > >> > which doesn't? Could it just be potassium's lower saturation
point
> > >that
> > >> > makes it seem that way or is there a property of alcohol that
makes a
> > >> > potassium form do this whereas an ammonium form doesn't? Or is
this even
> > >> > true in your observations, and from a practical standpoint, at
what
> > >point?
> > >> > Any conjecture would be appreciated.
> > >> >
> > >> > My reason for asking this is just thinking about the addition of
alcohol
> > >> > in
> > >> > a coating solution in gum printing that has been suggested in the
past,
> > >to
> > >> > make it thinner and easier to coat, whether this is viable with
> > >potassium
> > >> > dichromate.
> > >> > Chris
> > >> >
> > >> >
> > >> >
> > >>
> >
>
> ---------------------------------------------------------
> Gordon J. Holtslander Dept. of Biology
> holtsg@duke.usask.ca 112 Science Place
> http://duke.usask.ca/~holtsg University of Saskatchewan
> Tel (306) 966-4433 Saskatoon, Saskatchewan
> Fax (306) 966-4461 Canada S7N 5E2
> ---------------------------------------------------------
Received on Thu Feb 26 22:20:29 2004