Acidity

“ In Massachusetts, also, the acidity must be equivalent to 41⁄2 per cent. of acetic acid, and cider vinegar must contain, at least, 2 per cent. of solid matter. The English standard of strength is 3 per cent. of acetic acid.
Analysis.—For the requirements of the United States Customs Service, the only estimations ordinarily made are the specific gravity, and a determination of the acidity. The former is accomplished by means of the specific gravity bottle; the latter, by placing 10 c.c. of the sample in a beaker, adding about 30 c.c. ”

“ The natural secretions of the human stomach are acid, and the acidity is subservient to the digestive functions. It cannot be superseded by artificial alkalinity without serious disturbance of nutrition; and the aim of treatment, in the case of all digestive derangements, should be to cure them by changing the conditions under which they arise, not to palliate them for a time by the neutralisation of acid, which may, indeed, give relief from present trouble, but which leaves unaltered the conditions upon which the trouble really depends. ”

“ OF ACIDITIES. The food of children being for the most part of an acescent nature, it readily turns sour upon the stomach, especially if the body be any way disordered. Hence most diseases of children are accompanied with evident signs of acidity, as green stools, gripes, &c. These appearances have induced many to believe, that all the diseases of children were owing to an acid abounding in the stomach and bowels; but whoever considers the matter attentively, will find that these symptoms of acidity are oftner the effect than the cause of their diseases. ”

“ Although the acidity contained in stagnant water which has, in its course, been impregnated with animal and vegetable particles, cannot be very considerable, yet it will be more safe, and prudent, to prevent the formation of such acids, by an early attention to the purity of the water. ”

“ The reason that acidity is not more frequently observed and attended to than it is, is because of its being sheathed or covered by the unattenuated sweets, or fermentable matter of the wash that remains undecomposed. ”

“ It followed from this view, that the metallic calces were combinations of metals with oxygen; and on examining the products of certain inflammable bodies, and finding them to be acid, the conclusion was extended by a plausible analogy to other acids whose bases were unknown, and the general proposition was established that oxygen was the universal principle of acidity; that acids resulted from the union of a peculiar combustible base, called the radical, with the common principle, oxygen, technically termed the acidifier. ”

“ Any body may easily conjecture that the Acidity of the Stomach was sufficiently strong to set upon the two aforesaid Metals, being of a Salt nature, and of an easie Solution, and to reduce them so far as to cause them to display their hidden Vertues. But now the Stomach is not endued with so strong an Acidity, as to be able to set upon and dissolve Gold and Silver, being Metals as ’twere void of Salt, and admitting no Solution there. ”

“ The mean acidity of the gastric juice, whether pure or mixed with food, is equivalent to about 1.7 grain of hydrochloric acid per 1,000, never falling below 0.5, or rising above 3.2 grammes. The quantity of liquid present does not seem to exert any influence on the degree of its acidity, which is augmented by wine and alcohol, and lessened by cane-sugar. The gastric juice is more acid while digestion is going on than during the intervals of the process; its acidity seems always to be increased as digestion is drawing to a close. ”

“ The acidity will not usually exceed 0.5 to 0.7 per cent, but in reality the serum will contain more than this, as the acid is formed in the serum, the butter fat having no role whatever. In a very rich cream, 40 to 50 per cent fat, it is impossible to develop more than 0.4 to 0.5 per cent of acidity, and the flavor of the butter will be low, because of the relation between the amount of acid and fat, while in a thin cream having the same acidity, the ratio between the amounts of fat and acid will be very different. ”

“ A heat inferior to that of boiling water, with which we must begin in order to warm the vessel gradually, brings nothing over, as hath been said, but an insipid water, destitute of all acidity. By increasing it nearly to the degree of boiling water, the distilled water comes to be slightly acid. ”

“ The distilled water impregnated with so small a quantity of vitriolic acid, having a more agreeable taste than when alone, and yet manifesting the presence of an acid by means of the syrup of violets; I subjected it to some other tests of acidity. It formed curds when agitated with soap, lathered with difficulty, and very imperfectly; but not the least ebullition could be discovered upon dropping in spirit of sal ammoniac, or solution of salt of tartar, though I had taken care to render the latter free from causticity by impregnating it with fixed air. ”

“ The difference between the organic acids, which are decomposed in the manner I have described, and the fixed composition of the mineral acids does not appear to have been sufficiently studied by those who prohibit fruit and vegetables on account of their acidity. It must never be forgotten that nearly all the organic compounds of potash, as they exist in vegetables and fruit, are acid. It may be desirable, in some cases, to add a little bicarbonate of potash to neutralize this excess of acid and increase the potash-supply. ”

“ Observations.—— Acidity in infants at the breast arises very frequently from the mother’s milk, and is best corrected by attention to herself, by avoiding indigestible food, and taking an anti-acid, such as carbonate of soda, or magnesia, once or twice a day; also to take a larger portion of animal food. Infants brought up with the spoon are peculiarly liable to acid, and require, if bowels are bound, a little magnesia, or if there be a looseness, chalk mixture occasionally mixed with their food. The green colour of the stools in infants, is an infallible proof of the presence of acid. ”

“ Rain in Washington, D. C., has an average acidity of 4.2, about as acid as a carbonated drink and more than ten times as acid as clean, unpolluted rain. This booklet will define acid rain, explain what effects it has on marble and limestone buildings, and show, on a walking tour, some of the places in our Nation’s capital where you can see the impact of acid precipitation.
The pH scale: pH = 7 is neutral, neither acid or alkaline; smaller pH values are acid, larger pH values are alkaline. A liquid with a pH of 3 is ten times as acid as one with a pH of 4. ”

“ Other bodies, on the contrary, seem to possess the same habitudes in the stomach as in the laboratory, and are alike influenced in both situations by the chemical action of various bodies, many examples of which are to be found under the consideration of the influence which solubility exerts upon the medicinal activity of substances; so again, acidity 56in the stomach is neutralized by Alkalies, and if a Carbonate be employed for that purpose, we have a copious disengagement of Carbonic acid gas, which has been frequently very distressing to the patient ”

“ Further, many kinds of wine have a somewhat acid taste. In Russia, kwas, especially in the acid form, is consumed in great quantities. Moreover, acid fruits and green vegetables are used as food, and they are either of themselves acid, or made so in the preparation. In medicine this instinct is likewise often made use of, and acid solutions, especially of hydrochloric and phosphoric acids, are prescribed in digestive disturbances. Finally, Nature itself constantly endeavours to prepare lactic acid in the stomach in addition to the hydrochloric acid. ”

“ This acid, united to the mineral alkali, makes Rochelle salt.
Every kind of wood, when distilled, or burned, yields a peculiar acid; and it is the vapour of this acid that is so offensive to the eyes in the smoke of wood.
A peculiar acid is obtained from most [Pg 57] vegetable substances, especially the farinaceous ones, and from sugar, by distillation with the nitrous acid. This seizes upon the substance with which the acid was united, and especially the phlogiston adhering to it, and then the peculiar acid of sugar crystallizes. ”

“ Acids may be considered as a peculiar class of burnt bodies, which during their combustion, or combination with oxygen, have acquired very characteristic properties. They are chiefly discernible by their sour taste, and by turning red most of the blue vegetable colours. These two properties are common to the whole class of acids; but each of them is distinguished by other peculiar qualities. Every acid consists of some particular substance, (which constitutes its basis, and is different in each,) and of oxygen, which is common to them all. ”

“ And the alcohols, with their allies, have no great power of resisting decomposition. These bodies, formed by the union of oxygen, hydrogen, and carbon, are also, as a class, chemically inactive. Formic and acetic are doubtless energetic acids; but the higher members of the fatty-acid series are easily separated from the bases with which they combine. Saccharic acid, too, is an acid of considerable power; and sundry of the vegetable acids possess a certain activity, though an activity far less than that of the mineral acids. ”

“ By consulting chemical systems, it will be found that this science of chemical analysis has made rapid progress in our own times. Formerly oil and salt were considered as elements of bodies, whereas later observation and experiment have shown that all salts, instead of being simple, are composed of an acid united to a base. The bounds of analysis have been greatly enlarged by modern discoveries [36] ; the acids are shown to be composed of oxygen, as an acidifying principle common to all, united in each to a particular base. ”

“ All of us know that vinegar and lemon juice have a sour taste, and it is easy to show that most acids are characterized by a sour taste. If a clean glass rod is dipped into very dilute acid, such as acetic, sulphuric, or nitric acid, and then lightly touched to the tongue, it will taste sour. But the best test of an acid is by sight rather than by taste, because it has been found that an acid is able to discolor a plant substance called litmus. ”

“ As experimental discovery advanced, the substances classed with acids have been constantly multiplying, and by a natural consequence the attributes connoted by the word have receded and become fewer. At first it connoted the attributes, of combining with an alkali to form a neutral substance (called a salt) ; being compounded of a base and oxygen; causticity to the taste and touch; fluidity, etc. The true analysis of muriatic acid, into chlorine and hydrogen, caused the second property, composition from a base and oxygen, to be excluded from the connotation. ”

“ For physical efficiency, the balance should be slightly alkaline. In the process of digestion minerals are oxidized into their chemical constituents of acids or alkalies. An excess of acid interferes with the normal alkalinity of the blood and secretions, prevents the normal absorption of oxygen and elimination of carbonic acid gas by the blood, hinders the work of the white blood corpuscles, irritates the nerves, lowering, therefore, the resistance and vitality, and irritates the kidneys. In the dietary, care should be taken to include alkali as Well as acid-forming foods. ”

“ Acetic or other similar organic acid may be used instead of the lactic acid, but sulphuric or mineral acids must not be used. The acid liquid is afterwards neutralized by ammonia, which is added when the bate is to be used, and there are then formed certain chemical compounds similar to those found in a dung bate.
The addition of the acid to the nutrient medium will immediately stop the growth of bacteria, but the acid is not added for that particular reason, but for the particular purpose set forth. ”

“ We do not know each step in the mode of action of any medicine or of our foods, either, for that matter; but we do not for that reason stop eating. We should still use the acids and alkalies for their effect on the patient as far as we can see it just as we shall still go on eating food because it nourishes us; but we shall be wise to stop talking so glibly about what we cannot see and do not yet know, the effect of those acids and alkalies on the chemistry of the blood. ”

“ A few secretions and excretions are naturally acid. Sometimes the body gets into a too acid state, but that is very rarely due to overeating of fruit. It is generally caused by pathological fermentation of food in the alimentary tract. The salts and acids of fruits are broken up in the stomach and help to form alkaline substances.
The water of the fruit is very pure, distilled by nature. The acid fruits are refreshing and helpful to those who have a tendency to be bilious. Fruits are cleansers, both of the alimentary tract and of the blood. ”

“ More exact methods of determining the amount of acidosis are the determination of the ratio between the total urinary nitrogen and the ammonia, the quantitation of the acetone, diacetic acid and oxy-butyric acid excreted, and the carbon dioxide tension of the alveolar air. These are rather complicated for average clinical use, however.
When the patient is sugar-free he is put upon a diet of so-called "5% vegetables," i.e. vegetables containing approximately 5% carbohydrate. It is best to boil these vegetables three times, with changes of water. ”

“ Make strongly alkaline with lime water, 25 grams of the milk, and evaporate to dryness on the water bath. Destroy the organic matter by igniting the residue. Dilute with 15 cc. of water and acidify with hydrochloric acid. Then add 1 cc. of the concentrated acid. Dip a piece of delicate turmeric paper in the solution; and if borax or boric acid is present, it will have a characteristic red color when dry. Ammonia changes it to a dark blue green, but the acid will restore the color. ”