From the digging of ancient Roman ruins, one knows that approximately 95% of the concretes and mortars constituting the Roman buildings consist of a very simple lime cement, which hardened slowly through the precipitating action of carbon dioxide CO2, from the atmosphere. This is a very weak material that was used essentially in the making of foundations and in buildings for the populace. Cato was the first Roman to write about making lime and early Roman construction methods about 200 years before Christ. This book is important to define the practice of making lime under quality control measures. Quality lime was important as it was an ingredient of Roman concrete, and without consistent quality lime the structures of Rome would not survive. (E. B. Rehaut, Cato the Censor on Farming. Octagon Books, Inc., New York, 1966, p. 64. )