Gram’s method

The surface structure of gram-negative bacteria (these are not stained by Gram s method and must be stained red with carbol fuchsin) is more diversified. It consists of an outer membrane whose main building unit is a lipopolysaccharide together with phospholipids and proteins. The actual cell... 

Type Gram-positive bacilli Principal Features Generally rod-shaped retain color when treated by Gram s method of staining Common Examples Bacillus anthracis, Clostridium tetani... 

Gram-negative bacilli Rod-shaped do not retain color by Gram s method Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa... 

Gram-positive cocci Generally spherical or ovoid in shape retain color by Gram s method Staphylococcus aureus, Streptococcus pneumoniae... 

Actinomycetes Thin filaments that stain positively by Gram s method Actinomyces israelii Nocardia... 

Gram s Method.—This is a method of differential bleaching after a stain. The cover glass preparations or sections are passed from absolute alcohol into Ehrlich s anilin gentian violet, where they remain one to three minutes, except tubercle bacilli preparations which reniain commonly twelve to twenty-four hours. They are then placed for one to three minutes (occasionally five minutes) in iodine potassium iodide water (iodine crystals i, potass, iodide 2, water 300), with or without washing lightly in alcohol. In this they remain one to three minutes. They are then placed in absolute alcohol until sufficiently bleached, after which they are cleared in clove oil and mounted in balsam. 

Gram-negative Losing the stain or decolorized by alcohol in Gram s method of staining, a primary characteristic of bacteria having a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of Hpoprotein and Hpopolysaccharide. [EU]... 

Gattermann s Method.— Accoiding to this method the diazonium bromide is first picparcd and then decomposed by finely divided metallic copper. The 50 grams /-toluidine is dissohed in 200 c.c. liydrobromic acid previously diluted with too c.c. water and diazoliscd in the usual way. To this solution... 

Preparation of HRh(CO) (P< 3)3. The complex was prepared through Wilkinson s method (24) and modified according to Rehder-Stirnweis (25). It is important to prepare relatively large quantities (about 10 grams) because small batches gave impure products. 

Possetto s method of testing 1 is as follows To 250 c.c. of boiling water contained in a porcelain dish are added first 20 c.c. of 95% alcohol arid 2 c.c. of 10% ammonia solution and immediately afterwards 30 grams of the material. After about 5 minutes boiling—when it is considered that the liquid is sufficiently coloured—cold water is added and the solid allowed to settle. The liquid is decanted into another dish and, after slight acidification with 10% hydrochloric acid, a small skein of defatted wool (0-5 gram) boiled in it for 10 minutes. If the wool remains yellow after repeated washing with water, the presence of a coal-tar colour is indicated. 

Arata s method, ioo c.c. of the wine are gently boiled in a flask to about one-third of its volume, 2 -4 c.c. of 10% hydrochloric acid and about half a gram of carefully defatted (with ether) white embroidery wool being then added and the boiling continued for 5 minutes. 

Chlorine.—1 gram of the substance is fused with nitre and sodium carbonate, the mass being dissolved in water, the solution acidified with nitric acid, and the chlorine determined either gravimetrically as silver chloride or volumetrically by Volhard s method. 

Extraneous Substances (Willenz s method).—1 gram of the substance is treated at a gentle heat with 100 c.c. of dilute hydrochloric acid (1 20), which dissolves the calcium salts (gypsum, chalk), effervescence indicating carbonate (chalk) the liquid is filtered by decantation and the insoluble part washed, the lime and any sulphuric acid being determined in the filtrate by the ordinary methods. 

Values of latent heat of vaporization L are taken from Landolt s Tables. They are in kilogram-calories per gram mole. Values of a, in reciprocal angstroms, are computed by Eq. (2.4), using data from Tables XXVII-1 and XXVII-2. Values of y, computed from Eq. (2.5), are to be compared with values computed by GrUneisen s method, tabulated in Table XXVII-2. 

The vapor pressure of beryllium and the effect of oxide and nitride films of various thicknesses were studied, using Langmuir s method. According to Langmuir, the vapor pressure P in atmospheres is related to the rate of evaporation m in grams per square centimeter per second at the absolute temperature T by the formula... 

This reaction is of particular interest inasmuch ns it constitutes nature s method of replenishing the free oxygen content of the atmosphere. The ollioiency of the process is evident when, to quote an example of medium assimilatory activity, it is remembered that one square metre of sunllower leaf can effect the decomposition of some to grams of carbon dioxide, and the simultaneous evolution of 30 grams of oxygen in one summer day of 15 hours duration. 

Colloidal palladium may also be prepared by Bredig s method, which consists in sparking between palladium electrodes under ice-cooled water containing a little sodium hydroxide (approximately 0-04 grams NaOH per litre).11... 

After treatment with hydrogen peroxide in 0.3 M hydrochloric acid at 70°C for 30 minutes in order to remove adsorbed organic matter, the silt fraction (4 to 74 ym diameter) was washed repeatedly with distilled deionized water to constant conductivity in order to remove any adsorbed acid. The specific surface area of this material was measured using Lawrie s (S) 1,10-phenanthro-line adsorption method. The cation exchange capacity per gram was determined by Chapman s ( ) method, in which the surface is first saturated with sodium by three successive washings with 1.0 M sodium acetate solution, followed by three successive washings with 1 M ammonium acetate, which is saved and analyzed for the displaced sodium. 

D. H. Martin where good efficiency is obtained over a wide spectral range. In addition, the recorded signal is 1 (s), i.e. only the oscillatory part of the interfero-gram. This method avoids the difficulty that spurious features are produced in (S ) because of a shift of the mean level I (oo) due to instrumental instabilities. 

Thanks to Jerry Trofimenko, we do not have to read Biology journals to learn about Scorpions. The people friendly varieties popularized by Jerry are so hard to resist. They are everywhere. The spread of Scorpion(ate)s also benefited by his unique multi-gram production methods. We will miss him. 

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