A Simple Sample Holder for Use in Thermostat Tanks One common method to keep samples in a thermastated water bath is to use a complex and cumbersome array of stands and clamps. This often places severe restrictions on the number of samples which can he accommodated and also the water can be lost by evaporation from these samples "high and dry," especially if the experiments are to continue wer a considerable time period a t temperatures significantly above room temperature. These problems were encountered in such a study and were adequately solved using a floating platform. In this case l-cm thick expanded polystyrene (waste packing from a delivered instrument) was used as a platform with holes, cut with a cork horer, far the sample tubes. Suitable tubes can conveniently be made to the required size from standard ground glass sockets by sealing the end t o give "test tubes." Although the grip of the polystyrene on the glass can hold the tubes in place it was found t o he better, especially with larger diameter tubes, to use a hole slightly larger than the tube and to keep this in place by means of a rubber washer, cut from appropriate diameter rubber tubing. Nmr tubes were mast conveniently held by the n i p of the ~olystvrene. In a d d ~ t ~ aInn ovrrcumlnp. the prohlrm uf .wcc,mmodntlng lnrgrr nurnlws of samples of differing A e s the fact that the platfarm a floatmz mt-nns that cherp snmplr. o w m a ~ n r a ~ n patd constant deprh in the harh rhruughout the experrment. Alw the p
