LARD AND LARD ADULTERATIONS. 539 



there is some foreign substance iu the lard. There is nothing in chemical analysis 

 that can compare in delicacy with the spectroscope ; the utmost reliance is placed 

 on this instrument, and it is used for the determination of the most serious and deli- 

 cate questions, and such as involve the issues of life and death. There are two forms 

 of this spectroscope, that of direct vision, and the micro-spectroscope ; the latter be- 

 ing a combination of the microscope and the spectroscope; both were employed in the 

 examination of the samples of the lard now in question. A piece of rubber was ar- 

 ranged with small cavities cut into it, and into one of these cavities "was placed a 

 specimen of pure lard, which had been previously melted and filtered ; in another 

 cottonseed oil ; in another lard with an admixture of 10 per cent of cottonseed oil ; 

 in another lard mixed with 20 per cent, of cottonseed oil (the lard used in all these 

 specimens had been filtered) and also one specimen of lard very carefully filtered ; the 

 cottonseed oil had not been filtered. These several samples were placed in front of 

 the spectroscope so that the light would pass through the liquids in succession. The 

 observation showed that in the case of the pure filtered lard there wa,s a very trivial 

 obscuration of the whole spectrum ; in the more carefully filtered lard scarcely any, 

 as the light passed through them ; in the sample of pure cottonseed oil the whole of 

 the upper part of the spectrum, from the upper or blue end down to the space between 

 Frauenhofer's lines E. and F., was obliterated. A second prism was then adjusted so 

 that the light from another source could pass through the spectroscope, revealing one 

 spectrum above another. These lights were so adjusted as that both had the same 

 degree of brilliancy. In this way they could observe in one spectrum the light pass- 

 ing through unobstructed and in the other passing through the specimen. Examined 

 in this way the filtered pure lard appeared as clear and brilliant in the oue spectrum 

 as the unobstructed light did in the other ; no difference could be detected. The pure 

 cottonseed oil being brought in the place of the pure lard, only one-half of the spec- 

 trum could be seen, the part only through which the light passed unobstructed, the 

 other half being entirely obliterated. The 10 per cent, mixture of cottonseed oil pro- 

 duced a very perceptible obscuration ; the 20 per cent, mixture much more, so that an 

 approximate estimate can be made by the degree of obscuration ; it would, perhaps, be 

 a rough estimate, but you can certainly say whether it is present or not. The samples 

 of Fowler lard 1, 2, and 3 were, after being heated and filtered, subjected to this test, .and 

 examined in the same way ; with them there was not the slightest obscuration of the 

 blue end ; the one spectrum had the same brilliancy as the other. Ho has not exam- 

 ined a great variety of oils with the spectroscope, and can not say what, if any, other 

 substance would similarly affect the light. Olive oil affects it differently ; that pro- 

 duces a dark baud on the lower part of the spectrum. These experiments were spe- 

 cially with reference to the detecting of cottonseed oil, and his experiments have 

 been sufficient to warrant him in claiming that he can certainly detect 10 per cent, 

 of cottonseed oil mixed with lard ; he tried it with an admixture of 5 per cent., and 

 found some obscuration ; his son claimed he could detect 5 per cent, every time, but 

 he (the witness) will not assert that he can do that, but he can a 10 per cent, mixt- 

 ure; he does not claim to be able to state that the adulteration is certainly cotton- 

 seed oil, but where there is no obscuration he will say that cottonseed oil is not pres- 

 ent, at least not to the extent of 10 percent. ; with practice, he thinks it probable that 

 a much less adulteration, by cottonseed oil, than 10 per cent, can be detected with 

 certainty. It is necessary that the lard should be melted and filtered, so that all the 

 particles of membrane can be removed from it. If melted and not filtered, there will 

 be a slight obscuration, but it will affect all parts of the spectrum alike ; if the lard 

 is properly filtered there will be no obscuration whatever; the presence of cotton- 

 seed oil affects the blue end only, and the degree of obscuration, from a slight dark- 

 ening to a total obliteration, depends on the amount of the cottonseed oil present in 

 the specimen. The micro-spectroscope developed the same effects as the spectroscope 

 alone, in respect to cottonseed oil. 

 He has tried theelaidino test, but has not been able to successfully use it in detect- 



