It will at once be seen from Table VII that nearly all of these mixtures are made up principally of one or more of the following substances: Borax, pyrethrum, cloves, and sassafras. The first two of these have been used for years in driving away vermin from the places they frequent. The second two, although not so often used, are doubtless efficacious, since it is commonly supposed that roaches, etc., are driven away by high-smelling oils and spices. The analyses, as given in the table, in most cases explain themselves, so it is unnecessary to go into further detail. Two samples, however, are worthy of further note, namely, 20504 and 23493. The first of these appears to be a by-product or an unpurified product in the manufacture of ultramarine (hence the sulphur, sodium, carbonate, and ultramarine), along with small amounts of borax and pyrethrum. Three of these, sulphur, borax, and pyrethrum, amounting on the whole to not more than one-third of the mixture, give to it its only value as an insecticide. Sample 23493, besides containing borax and sassafras root, also contains about 39 per cent gypsum, which adds weight, and is valueless as a vermin exterminator. Very fine powders, such as powdered gypsum, are said by some to drive away ants, since they seem to dislike to crawl through finely divided substances. ROACH PASTES. According to formulas published in chemical receipt books and pharmaceutical journals, these pastes all have free phosphorus as their active poisonous constituent. This is sometimes mixed with molasses and flour or corn meal, sometimes with glucose sirup and flour or corn meal, and sometimes with sugar, lard, and flour or corn meal. These preparations are very efficacious in ridding the house of cockroaches and rats, since they eat the paste and are killed outright instead of being driven away to some other place. Great care should be taken in the use of such preparations, since when taken internally they are poisonous to human beings and household animals. METHODS OF ANALYSIS AND DISCUSSION. The methods of analysis used for this class of compounds are as follows: Phosphorus."-Extract the phosphorus from a weighed quantity of the paste by repeatedly rubbing the sample up with small quantities of carbon bisulphid. Filter each time, keeping the filter covered to prevent oxidation. After all phosphorus is extracted treat the filtrate with a 5 per cent solution of silver nitrate, which will precipitate the phosphorus as silver phosphid. Oxidize the precipitated phosphid by treating with 30 to 40 cc of dilute nitric acid and shaking well. Finally, heat gently to oxidize the remaining phosphid and drive off a Chem. Zeit., 1893, XVII, 1244, 1245. the carbon bisulphid. Boil for ten minutes. Precipitate out the phosphate formed with molybdate solution and wash. Dissolve on the filter with ammonia and determine the phosphorus with magnesia mixture in the ordinary manner. While the accuracy of the above method is not great, it appears to be of sufficient value for the use to which it is put. Microscopic examination. This is made to determine whether wheat, corn, or any other form of starch is present. Reducing sugars.--A qualitative examination of a water extract of the paste is made with Fehling solution to see if reducing sugars are present. Polariscopic readings.-Treat a small unweighed quantity of the paste with water and pass the solution through a filter. Clarify with a little lead acetate and pass through another filter. Transfer 45 cc of the solution to a 50 ce flask, make up to the mark with water, mix, transfer to a 200 mm tube, and take a reading. Transfer another 45 cc of the solution to a 50 cc flask, add 5 cc of concentrated hydrochloric acid, mix, invert by heating to 68 C., taking fifteen minutes in so doing, filter, and again take a reading in a 200 mm tube at practically the same temperature as that of the former reading. If reducing sugars are present and the polariscopic reading is before inversion and after inversion, the presence of molasses is indicated. If reducing sugars are present and the polariscopic reading is + before inversion and practically the same + reading after inversion, glucose sirup is indicated. If reducing sugars are present and the reading is + before inversion and a less + reading after inversion, molasses which has been mixed with glucose may be present. ANALYSES AND DISCUSSION. Table VIII shows the results obtained by the above methods of analysis on five samples: Samples 20489 and 20490 appear to consist of phosphorus, flour, and molasses. Sample 20491 consists of phosphorus and flour with some sweetening substance that appears to be molasses mixed with glucose sirup. Sample 20492 is evidently composed of phosphorus, corn meal, and glucose sirup, and sample 20493 appears to be composed of the same substances, with perhaps a little molasses. TOBACCO EXTRACTS. Only four samples of this class of goods were examined, using the following methods of analysis: METHODS OF ANALYSIS AND DISCUSSION. Nicotine."-About 5 to 6 grams of the tobacco extract is weighed out in a small beaker. Ten cc of an alcoholic soda solution (containing 6 grams of sodium hydroxid, 40 cc of water, and 60 cc of 90 per cent alcohol) is added, followed by enough chemically pure powdered calcium carbonate to form a moist but nonlumpy mass. This is transferred to a Soxhlet extractor and extracted for about 5 hours with ether. The ether is evaporated off at a low temperature by being held over the steam bath, and the residue is taken up with 50 cc of a soda solution (containing 4 grams of sodium hydroxid in 1,000 ce of water). This is transferred by means of water to a Kjeldahl flask, capable of holding about 500 cc, and distilled in a current of steam, using a condenser through which water is flowing freely. A threebend outflow tube is used and a few pieces of pumice and a small piece of paraffin are added to the Kjeldahl flask to prevent bumping and frothing. The distillation is continued till all the nicotine has passed over. The amount of distillate varies from 300 to 500 cc, according to the amount of nicotine present. When the distillation is complete only about 15 cc of liquid should remain in the distilling flask. The distillate is titrated with standard sulphuric acid, using phenacetolin as indicator. One molecule of sulphuric acid is equal to two molecules of nicotine. Camphor.-The camphor in sample 2 I & W is determined in the following manner: Weigh out about 30 grams of the sample in a small beaker, add a large quantity of water to precipitate the camphor, filter and wash with cold water, spread the filter paper out on a flat surface and transfer the precipitate to thick dry filter paper by means of a thin spatula, and press between its folds. It is again transferred and pressed between filter paper. This is continued till it is dry. Transfer to a weighed watch glass and weigh again to obtain the weight of camphor. A correction is made based on the amount of camphor that is dissolved by a volume of water equal to that of the filtrate above. By this method low and only approximate results are obtained, but it is the best method we can find to work on mixtures of this description. a Wiley's Principles and Practice of Agricultural Analyses, Vol. III, p. 605. ANALYSES AND DISCUSSION. Table IX gives the results obtained by the above methods of analysis on four samples: a See correspondence with manufacturers, page 62. The following formula for this substance is placed on the bottle: 37 per cent nicotine, 23 per cent camphor, 32 per cent pure alcohol, remainder, other essential ingredients. See correspondence with manufacturers, page 60. Both samples 19687 and 22288 contain very small quantities of nicotine, and are consequently not good tobacco extracts. Sample 22289, containing 26.01 per cent nicotine, is a good tobacco extract. Although sample 2 I & W has not as much nicotine and camphor as are given in the formula on the bottle, as an insecticide it will be apt to give good results in actual practice. MISCELLANEOUS SOLID INSECTICIDES AND FUNGICIDES. The methods of analysis of the compounds under this heading are given in only a few cases, because they are so numerous and because most of them would immediately occur to anyone with a chemical training. METHODS OF ANALYSIS AND COMPOSITION OF COMPOUNDS. BUG DEATH. [Serial No. 19555.] Method of analysis.--The moisture determination is made by drying the substance for 12 hours at 100° to 105° C. The residue is heated to dull redness for volatile matter. For all of the other constituents 2 grams is dissolved in aqua regia by prolonged boiling. What remains is weighed as sand. The filtrate from this is made to 250 cc and onehalf taken for analysis, about 3 or 4 cc of concentrated sulphuric acid are added, and the solution evaporated until white fumes come off and no odor of nitric or hydrochloric acid remains. It is diluted with water, filtered, washed with water containing a little sulphuric acid, and finally with 60 per cent alcohol. The lead sulphate thus obtained is burned and weighed with the usual precautions. Sodium carbonate is added to the filtrate, and the precipitated zinc and iron washed carefully, dried, finally transferred to a weighed crucible, and carefully separated from the filter. The filter is burned in another crucible after treatment with concentrated nitric acid. The residue is again treated with concentrated nitric acid evaporated to dryness and burned. The other crucible is heated with the Bunsen flame, and the combined residues reported as zinc oxid+ferric oxid. The residue is dissolved by digestion with hydrochloric acid, and potassium hydroxid added till the iron is precipitated and the zinc has gone into solution. The precipitate is washed, dissolved in hydrochloric acid, precipitated again with ammonia, and finally washed, dried, burned, and weighed as ferric oxid. Composition of Bug Death. Sand Volatile, besides moisture (principally NH, Cl and some Lead oxid Zinc oxid Ferric oxid Per cent. 4.35 .73 3.27 1.93 85.17 4.38 99.83 This compound contains only 3.27 per cent of those constituents which would give it any value as a plant food, so that it would not give very good results in this direction. As to its value as an insecticide, it is reported as not having any appreciable effect on bugs when applied at the rate of 40 pounds to the acre. When applied at the rate of 100 pounds to the acre it kills the bugs but also burns some of the plant leaves. It is too expensive for general use." This substance is evidently a sample of partially dehydrated ferrous sulphate mixed with about 35 per cent sand and carbon. The green vitriol is very commonly used as a fungicide, but the other 35 per cent is inert in its action on insects. a Sixteenth Annual Report of the Maine Agricultural Experiment Station (1900). |