Tuesday, 20 March 2012

08:10 – The methyl cellulose arrived yesterday, along with a bunch of other chemicals. I’ll make up the solution later this week.

Methyl cellulose is interesting stuff. It’s freely soluble in cold water, but insoluble in hot water. One might therefore reasonably assume that the way to make up a solution of it is to dissolve it in cold water, but that doesn’t work very well. No matter how careful you are, if you mix methyl cellulose powder with cold water, it forms clumps that are almost impossible to get into solution. The trick is to make a suspension of the stuff in water at about 85 C to prevent clumping, and then pour that suspension slowly and with constant stirring into ice cold water. The tiny particles in suspension immediately dissolve in the cold water, forming a homogeneous solution. Alternatively, one can simply make a suspension of the full amount of methyl cellulose powder in hot water and then stick the beaker in the freezer to cool it down rapidly, before the suspension has time to settle out.


The biology book is proceeding on schedule. We’re supposed to receive the QC2 PDF Thursday. We then have Thursday and Friday to review it and make any final minor changes. Once that’s complete there’ll be an index review, followed by the book going to the printer on 6 April.

3 thoughts on “Tuesday, 20 March 2012”

  1. RBT wrote:

    “Alternatively, one can simply make a suspension of the full amount of methyl cellulose powder in hot water and then stick the beaker in the freezer to cool it down rapidly, before the suspension has time to settle out”

    Pardon the ignorant chemistry question, but can you just filter the clumps out? Would the cost of wastage be too high? And if you get a non-clumpy solution to begin with can any handling or storage errors result in clumps forming?

  2. Filtration would be problematic because the methyl cellulose solution is pretty viscous. Think pancake syrup.

    The stuff is stable once it’s made up. If it’s stored at high temperature, the solid methyl cellulose will form a suspension or a colloid, but as soon as the temperature decreases it’ll go back into solution.

  3. Hot here. And excessively humid. Since I have returned from Euroland, we have basically had no spring or fall; spring temps have gone from freezing to 80’s F and back to freezing in the fall. Usually, our spring and fall are the respite from high humidity, but not for the last few years, and not now. Into the 80’s today, breaking all kinds of records. A check with the folks in Berlin reveals that–except for their unusually cold winter after the first of the year–it is a normal year for them. Everyone was wearing jackets for pics taken last weekend, while I have not used my jacket in well over 2 weeks. Could god be punishing us for some sins?

    Nah.

    I may be saving on heat, but I’ll be ding-danged if I will turn the air-conditioning on before April! 80 in the office at the moment. Windows locked closed since installing the central air. Ugh.

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