Sunto.

Si studia il problema del magnetismo indotto in un cilindro circolare di lunghezza finita, per influenza di un campo magnetico qualsiasi, riducendo la questione alla risoluzione di equazioni integrali e si deduce la risoluzione esplicita nel caso del cilindro di lunghezza infinita, già considerato daKirchhoff.

Si risolve anche esplicitamente il caso in cui il cilindro di lunghezza finita diventi di sezione tanto piccola da poterlo considerare un filo.

Summary

Accurate data on the thermal conductivity of 56 species of Indian timbers, varying in density from 265 Kg./m.³ to 1310 Kg./m.³ in the air-dry condition at about 20°C., are reported.

The data represent the first set of results covering this entire range of density reported from a single laboratory.

The influence of convection and radiation on the conductivity of wood is discussed and the results compared with those of other investigators.

A special case of a problem discussed in a previous paper is treated in greater detail. An equation in the three variables, errors, trials and number of possible choices, is developed and compared with the results of an experiment performed under conditions closely approximating those required for the development of the equation. The agreement is excellent.

The approximate equation is derived for the rate of constriction of a dividing cell, describing the phenomenon from its early stages. The equation previously derived by G. Young for the case when the constriction has already considerably progressed is obtained as a limiting case.

Summary

A survey of past work on the nuclear methylation and ethylation of resorcinol and phloroglucinol derivatives is given and a mechanism for this reaction suggested. The nuclear methylation of β-resorcylic aldehyde has now been carried out giving rise to a good yield of the product (A). Its constitution as 4-methoxy-3-methyl-2-hydroxy benzaldehyde has been established in two ways: (i) A sample of 4-methoxy-3-methyl-2-hydroxy benzaldehyde was prepared according to the synthetic method of Jones and Robertson and compared with (A). (ii) The corresponding coumarin was prepared from (A) and was identified as 7-methoxy-8-methyl coumarin by comparison with the compound obtained by independent synthesis, starting from 2-methyl-resorcinol and passing through 7-hydroxy-8-methyl-coumarin as an intermediate stage. The same coumarin was also prepared by the reduction of umbelliferone-8-aldehyde and subsequent methylation.

Summary

The kinetics of acid hydrolysis of ethyl acetate, ethyl propionate and ethyl chloracetate in glycerol-water system has been studied. Both viscosity and dielectric constant influence the reaction and a close correlation of the parameters of the reaction velocity equation is noticed.