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The usefulness of the physical barrier of a paper sack against insect infestation, particularly by Tribolium castaneum Herbst. in stored decorticated groundnuts in Northern Nigeria was studied. Laboratory trials and open-air field tests showed that the storage of uninfested nuts in paper sacks preserved quality and reduced losses to a greater extent than did conventional hessian sacks. Previously infested groundnuts stored in paper sacks showed lower quality and greater losses in weight than similar nuts in hessian containers. Paper sacks with a sleeve valve for filling were more proof against insects than open-mouthed paper sacks and both types were particularly successful when situated either in the upper layers or in the interior of a stack in the open air.

Summary. Examiners are often advised that, if one examination paper is to have twice the weight of another, it is only by the former's having twice the S.D. of the latter that the required effect will be achieved. But precisely what is the effect which is called ‘having twice the weight’? And will doubling the S.D., in fact, achieve it? The answers call for a definition of Weight. Some established definitions are examined, and it is shown that, on these, doubling the S.D. will only rarely have the effect promised. A simple definition is proposed, which appears to be in accord with examiners' intentions, and which is such that a paper's weight is directly proportional to its S.D.

This paper calls attention to an experimental design which enhances the efficiency of the technique described by B. F. Houston and R. A. Huffman [3]. This alternative design is a modification of the simplex lattice design developed by Scheffe [6] for the mixture problem. While not possessing the optimal statistical properties of the central composite design proposed in [3], such as minimum bias and minimum variance, this modified design is optimum with respect to the number of design points employed; hence, it is the minimum cost design. Further, the design proposed in this note is excellent for use in multiple-block experimentation, which is very often required with constrained systems.

In this note the authors call for a change of the optimality criteria given by Theorem 3 in section 5 of the paper of W. Szwarc “On Some Sequencing Problems” in NRLQ Vol. 15, No. 2 [2]. Further, two cases of the three machine problem, namely, (i) ≦ and (ii) ≦ are considered, and procedures for obtaining optimal sequences in these cases are given. In these cases the three-machine problem is solved by solving n (the number of jobs) two-machine problems.

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Before the standard affinity of dyeing — Δu± can be determined, it is necessary to develop a theory of the dyeing process. This theory should indicate clearly the measurements that must be made and the manner in which they must be interpreted in order to determine — Δμ±. Each existing theory of dyeing provides a theoretical model of the dyeing process with which the behaviour of the real dyeing system may be compared. Only when the theoretical model is correct in every respect is — Δμ±, calculated with the aid of the model, a true thermodynamic variable, and only then can reliance be placed upon the values that are obtained for this parameter. From the variation of — Δμ± with the absolute temperature T, it is possible to determine the standard heat of dyeing ΔH±, which then enables the standard entropy of dyeing ΔS± to be derived. The measurement and the significance of the thermodynamic variables — Δμ±, ΔH±, and ΔS± are discussed in detail, with particular reference to the mechanism of dyeing of synthetic-polymer fibres with disperse dyes.