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The quick and the dead

CI/SfB q Reprints of two treatises on lime from the 1830s provide architects and historians with new understanding of the material's use

The introduction by Michael Wingate to Pasley's Observat ions on Lime 1of 1838 outlines the historical importance of the research Pasley describes in his informative summary of early developments in the science of hydraulic limes and cements.

Pasley's original book was in two parts, the first a long series of his own practical experiments to develop an artificial cement for military uses, the second part summarising earlier reports of research on building limes. This second section of Pasley's book is the one repr inted.

Pasley's descriptions cover the research and development of hydraulic limes, mortars and concrete by wellrespected scientists of the age, and deal with a wide range of materials including Hamelin's Patent Mastic, Benson & Co's Metallic Cement and linseed oil for hardening stucco. The methods of preparing these compounds are outlined and often referenced to the buildings for which they were used. Pasley describes the practical problems confronting the engineer at the time and their solutions. For example, laying bridge foundations 25 feet under water in rapidly flowing rivers.

Many of the historic landmark accounts in the science and development of building limes summarised by Pasley are extremely rare today. For example:

John Smeaton's observations on limes and cements including the narrative of building the Eddystone Lighthouse (1756-9) Dr Higgins' patent for 'cheap and durable Water Cement or Stucco, for building, repairing and plastering Walls, and for other purposes' (1780) Thomas Telford's description of the construction of the Menai Strait suspension bridge, completed in 1826 Records of the first (lime) concrete used for foundations in England, by Sir Robert Smirke (1817) Specifications for hydraulic mortar and concrete mixes are given by scientists, engineers and architects from European countries, including Sweden, Germany and France. There is also a small section on Indian stuccos, particularly Madras Chunan. Magnesia was proposed for use in India, as a hydraulic cement (1826).

Generally, this is an informative study of the research and development of natural and artificial hydraulic limes and cements in Europe during the eighteenth and early part of the nineteenth centuries.

It is unfortunate that the reports by Pasley are often marred by derogatory comments about the research of others, particularly Vicat. So it is right that Donhead has at the same time republished the English translation of Vicat's Treatise, allowing him to speak for himself.

Vicat's Treat ise Michael Wingate also introduces Vicat's Mortars and Cements 2of 1837, appraising Vicat's involvement with the research, development and production of hydraulic limes. Vicat drew together earlier research and arrived at his conclusions after extensive experiment. It is perhaps the most important text of the period on limes.

The title of this treatise explains a good deal about the book while allowing us to savour the text. Vicat's title reads: 'A Practical and Scientific Treatise on Calcareous Mortars and Cements, artificial and natural; containing directions for ascertaining the qualities of the different ingredients, for preparing them for use, and for combining them together in the most advantageous manner; with a theoretical investigation of their properties and modes of action. The whole founded upon an extensive series of original experiments, with examples of their practical application on the large scale.

By L J Vicat, engineer in chief of bridges and roads; formerly pupil of the 'Ecole Polytechnique'; member of the legion of honour, etc, etc, etc. Translated with the addition of explanatory notes, embracing remarks upon the various new experiments, by Captain J T Smith, Madras Engineers, F R S, associate of the Civil Engineers Institution, Late President of the Edinburgh Philosophical Society'.

Following this lengthy title, the author's preface summarises the problems facing engineers of the day. Captain Smith's preface makes the fundamental point that cements that require grinding will be produced industrially and will be preferred by manufacturers for largescale application whereas natural hydraulic limes, of whatever kind, may at all times be prepared by the common workman without machinery.

The book begins with field tests for establishing the class of a lime, followed by descriptions of lime kilns and lime burning. Vicat describes research, development and manufacture of artificial hydraulic limes in France. Captain Smith's footnotes compare these with those of England.

Chapters on slaking and hydraulic lime, and the preparation of mortars and natural and artifical 'Pouzzolanas' follow, including field tests and notes on production, and summarising mortars using various classes of lime, pozzolanas and aggregates. Methods of preparing and placing durable mortars to withstand severe conditions, including constant damp, are set out, and the importance of after-care outlined. Natural cements are discussed, including the English 'Roman Cement'. A chapter is devoted to comparisons of the Egyptian, Greek and Roman mortars used by Vicat and his contemporaries.

The second half of the book consists of notes on the chapters and comments by the translator, tables packed with analyses of limes, mortars and pozzolanas, and a substantial index. From the cement analysis of the pyramid of Cheops to the day-to-day practice of the 1830s, the book is an extremely rich source of information for the historian.

Stafford Holmes is a partner in Rodney Melville and Partners

1 Observations on Limes. C W Pasley, 1838. Reprinted by Donhead Publishing. £23.00

2 Mortars and Cements. L J Vicat, 1837. Reprinted by Donhead Publishing. £30.00

LASER CLEANING IN CONSERVATION

Martin Cooper's book* takes the view that airbrasive cleaning of sculpture has reached its limit of fine control; further improvement requires a change of technology, to lasers. He describes laser technology and recent developments towards making it a portable and practicable, if still expensive, tool for conservators.

* Laser Cleaning in Conservation: an Introduction . Martin Cooper. Butterworth Heinemann. 98pp. £40.

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