Cocaine is manufactured from the dry leaves of the Erythroxylon coca, which grows in the valleys of the East Cordilleras of South America—­i.e., in the interior of Peru and Bolivia.  The fresh leaves contain 0.003 to 0.006 per cent of cocaine, which percentage decreases considerably if the leaves are stored any length of time before being worked up.  On the other hand, the alkaloid can be transported and kept without decomposition.  This circumstance caused the author to devise a simple process for the manufacture of crude cocaine on the spot, neither Peru nor Bolivia being suitable countries for complicated chemical operations.  After many experiments, he hit upon the following plan:  The disintegrated coca leaves are digested at 70 deg.  C. in closed vessels for two hours, with a very weak solution of sodium hydrate and petroleum (boiling between 200 deg. and 250 deg.  C).  The mass is filtered, pressed while still tepid, and the filtrate allowed to stand until the oil has completely separated from the aqueous solution.  The oil is drawn off and carefully neutralized with very weak hydrochloric acid.  A white bulky precipitate of cocaine hydrochloride is obtained, together with an aqueous solution of the same compound, while the petroleum is free from the alkaloid and may be used for the extraction of a fresh batch of leaves.  The precipitate is dried, and by concentrating the aqueous solution a further quantity of the hydrochloride is obtained.  Both can be shipped without risk of decomposition.  The product is not quite pure, but contains some hygrine, traces of gum and other matters.  Its percentage of alkaloid is 75 per cent., while chemically pure cocaine hydrochloride (C_{17}H_{21}NO_{4}.2HCl) contains 80.6 per cent. of the alkaloid.  The sodium hydrate solution cannot be replaced by milk of lime, nor can any other acid be used for neutralization.  Alcohol or ether are not suitable for extraction.  A repetition of the process with once-extracted coca leaves gave no further quantity of cocaine, proving that all the cocaine goes into solution by one treatment.  The same process serves on the small scale for the valuation of coca leaves. 100 grms. of coca leaves are digested in a flask with 400 c.c. of water, 50 c.c. of 1/10 NaOH (10 grms. of NaOH in 100 c.c.) and 250 c.c. of petroleum.  The flask is loosely covered and warmed on the water bath for two hours, shaking it from to time.  The mass is then filtered, the residue pressed, and the filtrate allowed to separate in two layers.  The oil layer is run into a bottle and titrated back with 1/100 HCl (1 grm. of HCl in 100 c.c.) until exactly neutral.  The number of c.c. of hydrochloric acid required for titrating back multiplied by 0.42 gives the percentage of cocaine in the sample.  The following are some of the results with different samples of coca leaves of various age: