Residue

“ If the materials for analysis be soft solids, especially the stomach, intestines, liver, and the like, commence at once with the process of charring with sulphuric acid. In the case of the urine, examine both the liquid and sediment. Filter the liquid, transmit chlorine to excess, let the product rest twenty-four hours, filter, evaporate to dryness, dissolve the residue in water acidulated with hydrochloric acid, and test the solution both with copper-leaf and by agitation with ether. ”

“ After moistening with concentrated hydrochloric acid the mass is boiled with water, filtered, and the filtrate examined according to the ordinary methods for silicic acid, alumina, iron, lime, magnesia, and alkalies. The residue after 356treatment with concentrated sulfuric acid is dried, but not ignited, and boiled with a concentrated solution of sodium carbonate with the addition of a little caustic soda, filtered, heated, and the silicic acid separated from the solution. ”

“ Dissolve the suspected stain in a few drops of normal salt solution upon a slide. If a liquid is to be tested, evaporate some of it upon a slide and dissolve the residue in a few drops of the salt solution. Let dry, apply a cover-glass, and run glacial acetic acid underneath it. Heat very gently until bubbles begin to form, replacing the acid as it evaporates. Allow to cool slowly. When cool, replace the acid with water, and examine for hemin crystals with two-thirds and one-sixth objectives. ”

“ The principle of residues is this: Subtract from any phenomenon those parts of it which are known to be the effect of certain antecedents, and what is left of the phenomenon is the effect of the remaining antecedent.
The most valuable feature of residues is its suggestiveness; an attempt to explain the “residual phenomenon” has led to many important scientific discoveries.
(7) The five methods are concerned with the establishment of causal connections between phenomena. Agreement suggests the connection while difference proves it. ”

“ Do not be in a hurry about doctoring a bath solution (in fact, it will be far best to have two solutions, one in use and one either resting or being doctored) , but give the light plenty of time to reduce the organic matter, and also to {16} volatilize the ether and alcohol; then filter the solution through filtering paper (don’t use blotting-paper) , as if it is attempted to filter through a pledget of cotton-wool the fine precipitate of organic matter quickly clogs the wool and stops the filtering. ”

“ Solids require relatively more of a given solution than liquids.
7. State of the disinfectant, whether solid, liquid or gas, and whether it is ionized or not. Solutions penetrate best and are therefore more quickly active and more efficient.
8. The solvent. Water is the best solvent to use. Strong alcohol (90 per cent. +) diminishes the effect of carbolic acid, formaldehyde and bichloride of mercury. Oil has a similar effect. The action is probably to prevent the penetration of the disinfectant. ”

“ When the water naturally existing in plants is expelled by exposure to the air or a gentle heat, the residual dry matter is found to be composed of a considerable number of different substances, which have been divided into two great classes, called the organic and the inorganic, or mineral constituents of plants. The former are readily combustible, and on the application of heat, catch fire, and are entirely consumed, leaving the inorganic matters in the form of a white residuum or ash. All plants contain both classes of substances ”

“ Decomposition of Water in the Plant.—In addition to the function which water performs in the plant, as the solvent of the different substances which form its nutriment, and hence as the medium through which they pass into its organs, it serves also as a direct food, undergoing decomposition, and yielding hydrogen to the organic substances. Its constituents, along with those of the carbonic acid absorbed, undergo a variety of transformations, and form the principal part of the non-nitrogenous constituents. ”

“ But it is essential for the best results that there should be running water, so that the substance in solution is carried away. If the sheets are merely washed in a large vessel, which has been filled with clean water, it must be obvious that, by the time some scores of sheets have been washed, the protein matter in solution on the surface of the sheets has been transferred to the washing water, so that the later sheets of the batch are liable to show the defect again on drying. ”

“ Moist animal tissues, by virtue of their porosity, allow soluble matters, which come into contact with them, to be dissolved by the water which they contain, and which oils their pores: if the matters are already in solution, they are imparted by their solutions to the water of the tissues. Gaseous substances are taken up in the same way. Water exists in nearly as large a proportion in vegetable as in animal substances. ”

“ When a difficultly soluble substance is formed in a solution beyond the point of saturation of the solution, the substance in question separates from the solution in a new phase, according to the principles just laid down. Ordinarily, if the substance is a solid, a precipitate is formed; if a gas, a gas escapes; if a liquid, a liquid separates out, which is immiscible with the solution in which it is formed. ”

“ If the mixture is deeply coloured, none will act characteristically. If carbonate of potass be present in such proportion as is often met with in the shops, the tests cannot be trusted to.
Process for Compound Mixtures.—The following method of analysis is applicable to all mixtures, organic and inorganic. Add water, if necessary, and filter; and if the fluid which passes through is tolerably free from colour, test a little of it with solution of starch and chlorine. ”

“ Rest the cover-slip, film side uppermost, on the rubber mat.
2. By means of a drop-bottle, cover the film side of the cover-slip with the selected stain, allow it to act for a few minutes, then wash off the excess in running water.
The penetrating power of stains is increased by (a) physical means—e. g., heating the stain; (b) chemical means—e. g., by the addition of carbolic acid, 5 per cent. aqueous solution; caustic alkalies, 2 per cent. aqueous solutions; water saturated with aniline oil; borax, 0.5 per cent. aqueous solution. ”

“ Why, when your sterilized organic infusion is exposed to optically pure air, should this generation of life de novo utterly cease? Why should I be able to preserve my turnip-juice side by side with your saline solution for the three hundred and sixty-five days of the year, in free connection with the general atmosphere, on the sole condition that the portion of that atmosphere in contact with the juice shall be visibly free from floating dust, while three days' exposure to that dust fills it with bacteria? ”

“ Wash well in distilled water till no more colour is discharged; if necessary, wash carefully with absolute alcohol.
4. Filter a few drops of the stain on to the film, warm as before, and allow the steaming stain to act for one minute.
5. Wash well in distilled water.
6. Dry and mount.
Note.—The flagella of some organisms can be demonstrated better by means of an alkaline stain or an acid stain—a point to be determined for each. Speaking generally, those bacilli which give rise to an acid reaction in the culture medium require an alkali; those which form alkali in cultivation require an acid. ”

“ VI. The distilled water must next be examined by various tests, to ascertain whether it materially differ from distilled common water; or whether it be impregnated with any saline or mineral particles, similar to those observed in the natural fluid, when first drawn from the well. In this process, if the water contain any common salt, it will, with a solution of silver, assume a white colour: if vitriol of iron be one of its ingredients, it will become black, on being mixed with pulverized galls. ”

“ In the complex mixtures which constitute the protoplasm of the living cell, this phenomenon of “adsorption” has abundant play: for many of these constituents, such as oils, soaps, albumens, etc. possess the required property of diminishing surface tension.
Moreover, the more a substance has the power of lowering the surface tension of the liquid in which it happens to be dissolved, the more will it tend to displace another and less effective substance from the surface layer. ”

“ C. Every liquid which, when placed in a white porcelain vessel to the depth of one inch, exhibits under daylight distinct color.
D. Every liquid which contains in solution, in every 100,000 [8] parts by weight, more than two parts of any metal, except calcium, magnesium, potassium and sodium.
E. Every liquid which in every 100,000 parts by weight contains in solution, suspension, chemical combination or otherwise, more than 0.5 metallic arsenic.
F. Every liquid which, after the addition of sulphuric acid, contains in every 100,000 parts by weight more than one part of free chlorine. ”

“ Next the object is dipped into the liquid, or if this is not possible the solution is applied thin but evenly with a brush, pencil, or rabbit’s foot. When the liquid has dried, the article is placed for a half hour in simple boiling water. If a very dark shade is desired the process is repeated until the required color is attained.
II.—Apply, by means of a sponge, a solution of crystallized iron chloride, 2 parts; solid butter of antimony, 2 parts; and gallic acid, 1 part in 5 parts of water. Dry the article in the air and repeat the treatment until the desired shade is reached. ”

“ If mercury be not thus detected, proceed to the solid matter left on the filter, by which the subject of analysis was in the first instance separated into a liquid and solid part. Examine this by evaporation to dryness over the vapour-bath, and charring with sulphuric acid in a retort with a receiver attached; and then subject the product to the same steps as those detailed above for the dried residuum of the liquid part. ”

“ Therefore this incomparable subject is called an universal solvent, because by its benefit, many incredible things are performed in the preparation of good Medicines, and also in the preparation of metals, yet let no man believe that it dissolveth metals swiftly and violently, like aqua fortis, aqua regia, or other corrosive waters, not in the least, but worketh altogether after another manner, viz. Vegetables and Animals are dissolved in digestion, by the moist way, in which solution, the pure parts are separated from the impure. ”

“ The conditions which regulate the solubility of bodies, and the power of solution, regarded either as a mechanical or a chemical process, are very obscure. We might be led to suppose, that those bodies possessing the largest amount of unoccupied space were capable of holding the greatest quantity of soluble matter dissolved. ”

“ Laundry Blue.—The soluble blue of commerce, when properly made, dissolves freely in water, and solutions so made are put up as liquid laundry blue. The water employed in making the solution should be free from mineral substances, especially lime, or precipitation may occur. If rain water or distilled water and a good article of blue be used, a staple preparation ought apparently to result; but whether time alone affects the matter of solubility it is impossible to state. ”

“ Take the case of elective affinity, which, by its very title, gives to these so-called dead substances the property of a power of choosing. As an example of what I mean generally let me remind you of a very common mineral, chalk, or carbonate of lime; in it a solid substance, lime, is combined with a colourless gas called carbonic acid. Now, the instant that another acid, say sulphuric acid, is brought in contact with chalk, what is the result? ”

“ Micro-organisms screened out in a mechanical way. The micro-organisms contained in the liquid will be to a large extent screened out in a mechanical way with the suspended matters and deposited on the surface and in the upper layers of the soil.
Retention of matters in solution after removal out of the liquid is due to physical and chemical agencies. ”

“ They absorb oxygen from the surrounding medium, air or water, and, in addition to certain inorganic substances, take into their bodies, as their proper nutritive material, complicated protein compounds, which they derive either directly or indirectly from plants. Through the oxidation of these compounds they form substances of a simpler chemical structure, such as carbonic acid, water, and ammonia, and discharge these through their bodies as waste. ”

“ A requisite of all chemicals to be employed is their ready solubility in water. Of substances intended for absorption [3] I have used but three, viz: iron, iodine, and extract of malt. The first of these I have employed [26] in anæmic and enfeebled conditions generally, but especially in chlorosis and chlorotic hysteria, with marked success. ”

“ The conditions necessary to bring a solid substance into a colloidal mixture with some liquid, or, in other words, to produce a suspensoid sol, require that the proportion of liquid to solid shall be large and some means of disintegrating the material which is to be dispersed into very fine particles. Many common chemical reactions, if carried out in very dilute solutions, result in the production of sols, especially if a small amount of some emulsoid is present in the reacting mixture ”