- Itinerary: University of California Lectures, Berkeley Lecture [Filed under LP Travel: Box #1.002, Folder #2.1]
- Letter from Chauncey Leake, The Ohio State University, to LP RE: Compliments LP on his appearance on the TV program, "Youth Wants to Know." [Letter from LP to Leake January 20, 1956] [Filed under LP Correspondence: (R: Correspondence, 1956), #341.2]
- Letter from H. Rotta, Scientific Review, to Mr. Piel, Scientific American, RE: Written in German. Apologizes for a mistake regarding copyrighted material in Scientific Review. [Filed under LP Correspondence: (Scientific American, 1948-1995), #374.9]
- Letter from Hans Rotta, Naturwissenschaftliche Rundshau, to Gerard Piel, Scientific American, RE: Letter in German regarding Naturwissenschaftliche Rundshau's alleged copyright infringement. [Letter from Piel to Rotta December 29, 1955] [Filed under LP Correspondence: (S: Organizational Correspondence. (Sa - Sc)), #374.9]
- Letter from James H. Hyde, American Members of the Institut de France, to LP RE: Invites LP to attend a luncheon at the University club as his guest. [Letter from LP to Hyde January 25, 1956] [Filed under LP Correspondence: (I: Correspondence, 1956), #185.17]
- Letter from John Leo Abernethy, California State Polytechnic College, to LP RE: Requests a report on the subject of LP's talk "The Genesis of Ideas" for the Journal of Chemical Education. [Letter from LP to Abernethy January 3, 1956] [Filed under LP Correspondence: (A: Correspondence, 1956), #12.22]
- Letter from John R. Pierce to LP RE: Apologizes for his delayed response to LP's December letter. Says he would like to visit Caltech and hear about LP's work on mental deficiency. [Filed under LP Correspondence: (P: Correspondence, 1956), #313.4]
- Letter from LP to Prof. Joshua Lederberg, The University of Wisconsin. [Letter from Lederberg to LP November 4, 1955] [Filed under LP Correspondence: (Lederberg, Joshua), #215.1]
4 January 1956
Professor Joshua Lederberg
Department of Genetics
The University of Wisconsin
Madison 6, Wisconsin
I am surprised to notice that your letter arrived here nearly two months ago. I have not had any special reason for postponing my answer just the usual one of having been busy with various jobs.
I have often pointed out, as you mention, that a crystal of a molecular substance can be considered as showing complementariness - each molecule is complementary in structure to the aggregate of the surrounding molecules. In the process of crystallization the molecules select the structure (the way of packing) that gives the greatest complementariness, and hence the greatest stabilization through intermolecular attraction.
One might ask, as you do, whether two different kinds of molecules, A and B, might not be able to pack together, in a crystal, better than the individual molecules can pack by themselves in the crystals of the separate pure substances. The answer is that this might happen sometimes and not other times. For example, when a racemic mixture of two optical isomers is allowed to crystallize, one obtains racemic crystals roughly half the time, and right-handed and left-handed crystals the other half of the time. In the same way, when salts are crystallized together, such as potassium chloride and magnesium chloride, one may obtain crystals of a double salt, or one may obtain two kinds of crystals, of the individual salts.
I have not so far made any reference to mixed crystals (solid solutions). I think that one can understand why mixed crystals in general form only between substances with very nearly the same molecular size and shape. A crystal of substance A, for example, has, when one molecule A is removed from inside it, a cavity into which this molecule fits neatly; in general a molecule B would not fit into this cavity, and hence in general A and B would not form solid solutions.
- Letter from LP to Raymond R. Edwards, University of Arkansas, RE: Regrets that he will be unable to visit Arkansas to give a lecture. Suggests the possibility of lecturing in future years. [Letter from Edwards to LP November 4, 1955] [Filed under LP Correspondence: (E: Correspondence, 1956), #112.22]
- Letter from Professor Bruce A. Benson, Physics Dept., Amherst College, to LP RE: Thanks LP for sending the title of his talk. Will expect to hear from LP later regarding his travel plans. [Letter from LP to Benson January 3, 1956] [Filed under LP Speeches: 1956s.19]
- Letter from R. I. Stirton, Oronite Chemical Company, to LP RE: Describes a program designed to stimulate interest in chemistry at a high school level. Requests names of Bay Area high schools whose graduates tend to be strong chemistry students. [Memo from Asquith to Wulf January 13, 1956] [Filed under LP Correspondence: (S: Correspondence, 1956), #379.4]
- Proposed Itinerary: Iowa State College, Ames [Filed under LP Travel: Box #1.002, Folder #2.1]