Laboratory assistants

We should also like to express once again our sincere thanks for the considerable help we have received from our laboratory assistants, Mr. F. C. Baker and Mr. F. E. Smith. 

Salt was first electrochemicaHy decomposed by Cmickshank ia 1800, and ia 1808 Davy confirmed chlorine to be an element. In the 1830s Michael Faraday, Davy s laboratory assistant, produced definitive work on both the electrolytic generation of chlorine and its ease of Hquefaction. And ia 1851 Watt obtained the first Fnglish patent for an electrolytic chlorine production cell (11). 

Eorensic science laboratories may have different missions and therefore conduct different types of testing on samples (21,22). Eor example, the United States Department of Justice, Dmg Enforcement Administration (DEA) forensic laboratories assist authorities ia criminal intelligence-gathering efforts. As such, DEA chemists routinely analyze both the iUicit dmg and excipient, the material used ia the cutting or diluting of the pure dmg, ia a given specimen. The excipient may provide information as to where the sample was produced. 

Joseph Black was born in Bordeaux, France, the fourth child of parents of Scottish extraction. His father was a native of Belfast engaged in the Bordeaux wine trade his mother was a daughter of an Aberdeen man who had settled in Bordeaux. In all. Black s parents had twelve children. At the age of twelve Black was sent to school in Belfast, and around 1744 proceeded to the University of Glasgow. Black followed the standard curriculum until pressed by his father to choose a profession. He opted for medicine. Black began to study anatomy and chemisti-y. William Cullen had recently inaugurated lectures in chemisti y that were to have a decisive influence on Black s career. Recognizing Black s aptitude, Cullen employed Black as his laboratory assistant. 

Significantly, when Carothers picked his own laboratory assistant, he chose, not a Protestant Midwesterner, but a young Russian Jewish immigrant. Carothers secured a Du Pont college scholarship for Joseph Labovsky... 

The laboratory assistant provides a gross description of the specimen on the requisition. 

He had taken the most interest in skilled workers, but that was normal since he was, in a way, a skilled worker himself. After the constmction was done (if it ever did get done), he would have craftsmen and laboratory assistants to help him operate it in the coming days of peace. One day a chemist-inmate had stopped him to talk about a new idea Ambros praised the idea and advised him to use it in a PhD. thesis "some day." The defense had not made the mistake of locating the chemist. Minskoff had found skilled workers, too, in Belgium, France, the Netherlands, and England. 

This book is intended for all those who are interested in organic pigments, especially chemists, engineers, application technicians, colorists, and laboratory assistants throughout the pigments industry and in universities and technical colleges. We have specifically avoided an in-depth discussion of the underlying scientific and theoretical framework, but there are references to the pertinent literature. 

Suppose that you are an analytical chemist. You want to test an unknown solution that contains some or all of the following ions silver, Ag+ arsenic, As + chromium, Cr + and sodium, Na+. Your laboratory assistant has already performed some tests on known solutions of these ions and has made the following observations ... 

If the laboratory assistant had to add 10 mb of 1 M sodium hydroxide to neutralize 5 mb of the sulfuric acid in his impromptu titration, what did he end up writing on the label for the concentration of the sulfuric acid in the bottle ... 

Preliminary approval by the instructor or laboratory assistant and signature of the experimenter. 

An analytical method is rugged when it shows, under different circumstances (different laboratory, different laboratory assistants, different times, etc.), the same results. 

Never pour unconsumed reagents back into their storage bottles. Hand them in to the laboratory assistant. 

Beware of water when working with metallic sodium and other alkali metals. Hand in trimmings of these metals to the laboratory assistant. Never throw them into the containers for waste. 

Pour the residues of mercury and arsenic compounds, metal cyanides, or compounds of the rare and valuable metals into special jars (take them from the laboratory assistant). 

When reduction is completed (how can this be established ), stop the heating and cool the apparatus to room temperature in a hydrogen stream (why ). Hand in the reduced copper to your instructor. Wash the unreacted zinc with water and hand it in to the laboratory assistant. 

Preparation and Properties of Selenium(lV) Oxide. Selenium compounds are very poisonous Hand in the prepared substances and residues o/ selenium preparations to the laboratory assistant. Run all experiments with selenium in a fume cupboard After work, thoroughly wash the ware and your hands. 

After completing work, thoroughly clean up your workplace and wash the ware with concentrated hydrochloric acid or aqua regia. Wash your hands with soap. Hand in the prepared substances and residues of tellurium preparations to the laboratory assistant. 

Let the ammonia evaporate. What substance remained in the apparatus Do not wash the apparatus with water, but hand it in to the laboratory assistant Why What explains the use of ammonia in refrigerating machines ... 

Preparation o/ Phosphorus Pentachloride. Prepare phosphorus trichloride or take the substance from the laboratory assistant. Assemble an apparatus as shown in Fig. 99b. Put the phosphorus trichloride into test tube 2 and connect reflux condenser 4 with water cooling to... 

Preparation of Sodium Hydroxide from Sodium Carbonate. Dissolve 14 g of anhydrous sodium carbonate in 100 ml of water. Pour the solution into a 250-300-ml round-bottomed flask. Put pieces of broken chamotte crucible on the bottom of the flask (for what purpose ). Fasten the flask in a stand so that a small space remains between the gauze and the bottom of the flask. Heat the solution in the flask up to boiling and add 8-10 g of triturated calcium hydroxide (in small portions). Insert a funnel into the neck of the flask (for what purpose ) and boil the solution during one hour, adding water from time to time to keep the volume constant. After cooling, filter the solution and measure its volume and density. Use the density value to determine the percentage of sodium hydroxide in the solution. Hand in the alkali solution to the laboratory assistant. 

Beryllium compounds are poisonous. Wash your hands ajter working with them. Hand in all residues o/ beryllium compounds to the laboratory assistant ... 

Put a small amount of the titanic acid on the lid of a crucible, dry it in a drying cabinet, and then roast it. What is obtained Write the equation of the reaction. How does the colour of the preparation change when roasted Is the previous colour restored after the substance has been cooled Dry the remaining amount of the titanic acid in the air and hand it in to the laboratory assistant. 

The experiments are demonstrated and explained by two students. After work, the remaining silver preparations and their solutions are to be handed in to the laboratory assistant. 

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