The first suggestion that bacteria might be agents in stone decay was probably that of Buchanan (1904) in a paper read before the Royal Philosophical Society of Glasgow in 1904. This paper contained evidence that bacteria, yeasts and moulds were associated with the decay of sandstones in the City of Glasgow, and included a brief sketch of the manner in which the autotrophic bacteria, sulphur bacteria, iron bacteria, and the nitrifying bacteria might play a part in sandstone decay. This paper was apparently unknown to later writers, Anderson (1910), Marsh (1923) and Fox and Harrison (1925), none of whom makes reference to it. In 1928 Buchanan published the results afresh with no important addition, but confirming his earlier work. Stutzer and Hartleb (1899) in an important paper, published five years before that of Buchanan, noted the solution of the lime of the cement on walls of reservoirs and dock sides. While the greater part of this solvent action was believed to be due to dissolved carbon dioxide in the water, part of it at least was attributed to the action of bacteria contained in a brown slime which covered the walls.

EARLY work on the occurrence of pectins and hemicelluloses showed that these substances were normally to be found in association in the cell-wall, the relative amount of each being dependent on the condition of the tissue, i.e. whether lignified or non-lignified [Clayson, Norris, and Schryver, 1921]. Subsequent work [Candlin and Schryver, 1928] indicated the existence of an intimate relation between the two classes of substances, since pectin was shown to undergo decarboxylation under the influence of alkali, yielding inter alia a substance of the hemicellulose type. The yield of hemicellulose obtained bythis treatment was invariably low, amounting only to 12-20 % of the pectin taken; further, these workers were unable to determine the nature of the products which represented the major part of the pectin. This might have been due to the fact that, as is well known, the sugars readily undergo profound changes in the presence of alkali, giving a variety of indefinite degradation products. It would follow therefore that if, as would seem possible from its accepted constitution, the pectin molecule yields sugars on decarboxylation, these latter would be destroyed immediately by the alkali present.Since, however, the decarboxylation of pectin is a reaction likely to throw some light upon the question of the relationship between certain of the cellwall substances, it is desirable to establish the nature of the substances other than hemicelluloses produced thereby. With this object it is necessary to employ a decarboxylating reagent which will not tend to destroy these other products, and it has been found possible to use hot water for this purpose. By this means, pectin has been shown to yield an insoluble substance, of the hemicellulose type, and one or more soluble substances, probably sugars.The insoluble product finally obtained appears to have undergone much more complete decarboxylation than the end-product (hemicellulose) described by Candlin and Schryver [1928]. From this insoluble product, a substance of the hemicellulose type has been separated, containing 6.2 % of uronic anhydride, and yielding a mixture of sugars on hydrolysis.The investigation of the soluble products is not complete, but it is thought that the observation that pectin can be decarboxylated by means of hot water is of sufficient interest to warrant the publication of a brief account of the work at the present stage.

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