During the past two years the writers hare studied a series of some forty alloys of gallium and indium covering the entire range of composition from pure gallium to pure indium. Search of the literature reveals no previous study of such alloys, this lack of study being due, no doubt, to the prerious scarcity of the two metals.In 1936 a progress report2 was presented covering the determination of the eutectic in the system gallium-indium. The present paper includes that work (which was not published) and completes the study of this alloy system. EXPERIMENTALBecause of the relatively high cost of the metals involved it was essential to work with small amounts and to develop a technique suitable to such work. In the customary methods for studying alloy systems amounts up to 15 or 20 g. are used and time-temperature curves are plotted. The eutertic alloy may be squeezed out and analyzed.In place of the usual time-temperature curve, the writers used temperature-temperature curves in which the temperature of the alloy was plotted against the temperature of its bath. This method is, of course, possible only where the alloys concerned have low melting points. Time was kept as nearly constant as possible in all determinations, the rate of temperature change being approximately one degree per minute.An iron-constantan thermocouple prepared of fine wire and coated with high-grade white shellac was used for determining the temperature of the alloy. During the work on the gallium side of the curve the alloy was used as the variable cold junction, the hot junction being placed in a constant-temperature bath of boiling water. The hot junction assembly was specially prepared and consisted of a Kjeldahl flask, to one side of the Present address:

Dehydration of the (3R)-hydroxyalkyl S-thioester (1) by yeast fatty acid synthetase to give the trans-2-enoyl derivative (2) occurs by means of a synelimination of the elements of water.

1. Fatty acid synthetase was purified to homogeneity from bakers' yeast. (2S,3R)-[3-3H~]Malic acid was prepared by incubation of fumarate with fumarase in tritiated water.3. [2-3H1 ,3-3H~]Fumarate was synthesised via a published procedure and used for the preparation of (2S,3S)-[2-3H~,3-3Hl]malate by incubation with fumarase in water.4. The above malates after being mixed with [U-14C]malate were converted into the 4-nitrophenyl hydrogen malates esterified at the C-4 carboxyl, the C-1 carboxyl and the 2-hydroxyl group being protected at intermediate stages as a 1,3-dioxolanone.5. The individual 4-nitrophenyl hydrogen malates were oxidised by zinc permanganate in carefully defined conditions to give 4-nitrophenyl hydrogen 2R-[U-14C, 2-3H1]-and 2S-[U-I4C, 2-3Hl]malonates.6. These 4-nitrophenyl hydrogen malonates were converted to the corresponding malonyl thiol esters by transesterification with coenzyme A or A'-acetylcysteamine under conditions of minimum tritium exchange and racemization.7. The malonyl thiol esters were immediately incubated with purified fatty acid synthetase and the cofactors necessary for the biosynthesis of fatty acids.8. The fatty acids, mainly palmitate and stearate, formed in these incubations were extracted and the 3H/14C ratio determined. Individual acids were recrystallised with carrier material or, after methylation, were separated by gas-liquid chromatography and the isotope ratio again determined.9. In this way it was shown that palmitate or stearate derived from the 2S-[U-14C, 2 -3 H~] malonyl thiol ester retained 51 % of the original tritium of the substrate whereas the acids derived from the 2R-[U-14C, 2-3H1]malonyl thiolester retained only 23 % of the original tritium. 2RS-[U-14C, 2-3H1] substrates gave an intermediate result.10. From a comparison of these results with those obtained previously using chiral acetate substrates it is deduced that carboxylation of acetyl-CoA catalysed by the chicken liver acetyl-CoA carboxylase occurs with retention of configuration at C-2. The results are shown to be in quantitative agreement with the theory, deduced from experiments with chiral acetates, that partial exchange of carbon-bound hydrogen occurs on the synthetase at some stage between malonate and fatty acid subsequent to the stereospecific elimination of hydrogen.11. The stereochemical course of individual reactions in the biosynthesis of fatty acids is discussed.In the foregoing paper [l] it was shown that the formation of fatty acids from chiral acetates. The fatty acid synthetase from chicken liver and bakers' discrimination between the R and S enantiomers in yeast possessed an overall stereospecificity in the these experiments was small because the small hydrogen isotope effect, operative in the acetyl-CoA carboxylase reaction, led to nearly equal proportions of tritiated malonyl-CoA species having R and Schirality. A partial, and therefore non-specific, exchange of hydrogen catalysed by the synthetase was also obAbbreviations. GLC. gas-liquid chromatography; TLC, thinlayer chrom...

An insecticidal exotoxin from Bacillus thuringiensis var. thuringiensis (Berliner) has been purified. The efficiency of each stage of the purification has been ascertained and the yield of toxic material estimated by means of a quantitative bioassay. It is shown that the exotoxin is an adenine derivative substituted at position 9 and having a molecular weight of approximately 825. It can be dephosphorylated enzymically or chemically under conditions that define the exotoxin as a phosphomonoester. This results in loss of toxicity, both to insects and to mice. Spectroscopic and kinetic data are presented which suggest that a beta-ribofuranosyl moiety may be attached to the adenine. Glucose and allomucic acid have been positively identified as hydrolysis fragments from the exotoxin. These results are discussed and compared with the results of others on similar (or possibly identical) compounds.

The recently increasing knowledge of dipoles and dipole moments together with the simplicity of their qualitative interpretation, suggest the use of the concept of polar molecules in elementary chemistry.