He states he has succeeded in obtaining oxygen from saliva by applying heat, and considers its presence of great value in as sisting the action of the secretion during the process of digestion, inasmuch as he found that, after exposing saliva to oxygen, so as to enable it to absorb the gas freely, he was en abled to convert, by its use, a much greater quantity of starch into sugar and gum (an action of which I shall hereafter treat), than by using saliva which had not been exposed to oxygen.
Dr. Wright's analysis of saliva is as follows : Water - - - - - 988'1 Ptyalin - - - - - 1.8 Fatty'acid Chlorides of potassium and sodium 1.4 Albumen combined with soda - .9 Phosphate of lime - Albuminate of soda - - '8 Lactates of potash and soda Sulphocyanide of potassium - .9 Soda - - - -5 Mucus, with some ptyalin - - 2'6 L'Heritier made analyses of saliva as ob tained from healthy persons, and gives the following a.s a mean of ten observations on adults: Water - 986'5 Organic matter - - 12'6 Inorganic matter - - -9 Of the organic matters 2.5 parts consisted of salivary matter, or ptyalin (probably not the ptyalin of Dr. Wright, but that described by Berzelius and Simon).
Saliva of Children.— Observations by L'He rider on the saliva of children showed the quantity of water to be greater in e,arly life. He gives the following as the mean of four analyses : Water - - 996.0 Organic matter - - 3-5 Inorganic matter - - .5 The ptyalin contained in the organic matter amounted to only 1.1.
Male and Female Saliva.—L'Heritier states that he could detect no difference between the saliva of men and women.
Enderlin has made several analyses of the ashes obtained from different specimens of saliva, and has found them to be similarly con stituted.
in his opinion, the tribasic phosphate of soda it contains is valuable as a solvent of the protein compounds. He denies the existence of alkaline lactates, not only because the ashes of saliva 3ielded no carbonate in his experi ments, but because he failed in detecting them by direct observation before incineration. His analyses of the ashes of saliva, as obtained from a large quantity of the secretion from dif ferent persons, yielded the following result :— The existence of the sulphocyanide of potas sium in the saliva is a matter of importance, and some difference of opinion is observed among chemists on the subject. The dis covery was originally announced by Trevi ranus, who noticed that saliva, when mixed with a neutral solution of the peroxide of iron, produced a dark red colour. This he regarded as produced by an acid, to which the name of " acid of the blood" had been given by Winterl, and which was afterwards known as the sulphuretted chyazic acid of Porrett. Tiedemann and Gmelin examined into this question, and found that the reaction de scribed by Treviranus really occurred on adding persalts of iron to saliva, and made expenments to discover whether the colour ation was produced by a sulphocyanide.
After lengthened observation, these physio logists arrived at the conclusion that such was the case, and procured other reactions besides such as were obtained by testing with iron, which satisfied them of the presence of sulphocyanogen.
Dr. Wright mentions sulphocyanide of po tassium in his analysis of saliva, and states that its quantity is always increased by locally stimulating the salivary glands, as by smoking or chewing sialogogues. The internal use of prussic acid or salts containing cyanogen in creases its quantity. It is also greatly in creased by the use of sulphur. Dr. W. says the presence of this salt is best detected in the alcoholic extract obtained from dried saliva. The sulphocyanide of potassiurn con stitutes, according to his observations, from 0 051 to 0-098 of the secretion. Kuehn tried to detect the presence of a solphocyanide in saliva, but failed. He could not prove the presence of sulphur either by the processes of Gmelin or Ure. Milller, also, was not satis fied by his observations that the red colour produced in iron resulted from the presence of sulphocyanog,en.
The properties and physiological uses of the saliva have been examined into by a great number of observers, and we find much valu able and curious matter for consideration in their general results.
General Properties.— Boerhaave and Hoff man ascribed a peculiar fermentative power to saliva, a subject which was subsequently more fully entered upon by Sir John Pringle and Dr. Macbride. The former observer experimented on certain anti-putrescent qua lities of the secretion, and found that raw meat putrefied slower after admixture with saliva. Another experiment of Sir John's deserves description m detail. He took two drachms of fresh meat, and the same quantity of bread, and to these added as much saliva as he supposed might be necessary for digestion. He beat up this mixture in a mortar, then enclosed it in a phial, and set it in a warm atmosphere for about two days. No signs of fermentation could be detected at the end of that time, but (luring the third day the bread and flesh rose in the water, a sediment formed, and bubbles were observed mounting in the liquor. The mixture now possessed a vinous smell. This action was observed to continue about twice as long as in a similarly conducted experiment made without saliva. ln the former case the fermentation was more gradual, and when complete the mixture possessed a pure acid flavour, and had no disagreeable smell.