Exercise 7. Calcium Nitrate

A saturated solution of calcium nitrate at 20° has a vapor pressure about equal to a column of mercury 6.5 mm. in height, while the average aqueous pressure of air at the same temperature is about 12 mm. Consequently, the conditions are favorable to deliquescence. 

Additional Exercises Calcium chloride, CaCl2-6II20 magnesium nitrate, Mg(N03)2-6H20. 

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First prepare a pure solution of calcium chloride by following the directions for the preparation of calcium nitrate in Exercise 7 but substituting hydrochloric acid for nitric acid and using 100 g. of marble. Do not add the excess of acid at the end of the operation but leave the solution strongly alkaline. It is also well to add about 10 cc. of bromine water to the acid solution while boiling it and before the addition of the slaked lime. This is to oxidize any ferrous salts that may be present. 

Additional Exercises Calcium hydroxide from sodium hydroxide and calcium chloride silver nitrite from silver nitrate and sodium nitrite manganese sulfite, MnSChSHsO, from manganese chloride and sodium sulfite (adding a little S02 to the solution) mercuric iodide from potassium iodide and mercuric chloride. 

Many studies have demonstrated that nitrates, calcium channel blockers, and blockers increase time to onset of angina and ST depression during treadmill tests in patients with angina of effort (Figure 12-5). Although exercise tolerance increases, there is usually no change in the angina threshold, ie, the rate-pressure product at which symptoms occur. 

Nitrates, (3-blockers, and calcium channel blockers are equally effective for relief of anginal symptoms. However, for prompt relief of an ongoing attack of angina precipitated by exercise or emotional stress, sublingual (or spray form) nitroglycerin is the drug of choice. 

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