Platinum Metals Review - Volume 12, Issue 4, 1968

When, as in many low torque potentiometers, contact pressures must not exceed a few grams the use of noble metals for both resistance wire and wiping contact becomes almost essential. As the factors that determine the electrical and mechanical behaviour of such low load sliding contacts have not yet been established, wiper/slidewire combinations are still selected on an empirical basis. This paper, based on a lecture recently delivered to the Fourth International Research Symposium on Electrical Contact Phenomena at Swansea, describes some results obtained on an apparatus in which the abrasion resistance and frictional characteristics of precision resistance alloys can be assessed in an objective manner at very low contact loads. Under such conditions metal is transferred from wiper to resistance alloy and the efficiency of this transfer process determines the electrical behaviour of these sliding contacts.

Platinum metals and their alloys featured in many of the fifty papers presented at the Fourth International Symposium, sponsored jointly by the Institute of Physics and the Physical Society and the Institution of Electrical Engineers, held in July at the University College of Swansea.

In recent years much research has been carried out on platinum group metal complexes, especially those containing the carbonyl ligand. As the nitrosyl group is a nitrogen bonded ligand which in its normal mode of bonding is isoelectronic with carbon monoxide, the chemistry of complexes containing co-ordinated nitric oxide is interesting, and they may have similar potential uses to the carbonyl complexes. This article outlines our present knowledge of the nitrosyl complexes and their mode of bonding.

The Fourth International Congress on Catalysis took place in Moscow during the last week in June, and was followed by three specialised Symposia, two of which were also held in Moscow and one in Novosibirsk. This Congress provided, as did its predecessors, a useful forum for the exchange of ideas and experience: an impression of the Congress and a review of the papers relevant to the platinum metals is given in this article.

A symposium organised by Professor E. Wicke and Professor T. B. Flanagan on the general topic of ’Hydrogen in Transition Metals’ was held in July at the Institute für Physikalische Chemie of the University of Münster. Most of the papers presented were concerned with palladium or its alloys and a brief review of these contributions is given here.

Credit must undoubtedly be given to the arsenic process of removing base metals from native platinum, and principally to its practice by Janety, the Master Goldsmith of Paris, in the years just before and during the French Revolution for leading to the first real exploitation of platinum as an industrial metal and for enabling its properties to be fully appreciated.