Journal of Applied Microscopy. 



123 



Mixture C— The ratio of the number 

 of grains of maize starch in mixture C 

 to the number of grains of wheat starch 

 was found to be 1:37.8. The ratio ob- 

 tained for the 10% mixture indicates 

 that this sample contains 15.7% of maize 

 starch; the 20% mixture, 16.2 per cent; 

 the 30% mixture, 15.2%; the 40% mixture, 

 14.4%; the 50% mixture, 18.5%. The 

 average of all of these is 16.0%. The 

 theoretical percentage of corn starch in 

 mixture C was 21.0%. 



It appears from these results that the 

 greatest difference between the theore- 

 tical percentage and the percentage 

 found was 5.0 per cent. These figures 

 were obtained by rapid work, and there 

 was no time to repeat the determina- 

 tions. By counting a considerably larger 

 number of microscopic fields for each 

 sample, say ten or twenty instead of 

 five, as was the case in these ex- 

 periments, the difference between the 

 theoretical percentages and percent- 

 ages found would undoubtedly be 

 considerably lessened. 



There are two very apparent errors in 

 the data given: The number of grains 

 of wheat starch to one of corn starch in 

 the 5 per cent mixture is undoubtedly too 

 high, while the corresponding number 

 for the forty per cent, mixture is evi- 

 dently too low. 



In the case of materials adulterated 

 with maize flour instead of maize starch 

 the difficulty of the determination 

 would undoubtedly be considerably in- 

 creased. If the nature of the maize pro- 

 duct used as the adulterant is known to 

 the operator the work will be consider- 

 ably facilitated. If possible, he should 

 obtain a sample of the material and pre- 

 pare mixtures of it with a good quality 

 of wheat fiour and use the data obtained 

 by counting the number of wheat and 

 maize starch grains contained therein as 

 a basis of comparison with unknown 

 samples. 



While it is not likely that it will often 

 be necessary or desirable to determine 

 quantitatively maize starch or other 

 maize products in mixture with wheat 

 flour, these results are offered as a sug- 

 gestion for persons who may find it 

 jiecessary to make such determinations. 

 E. E. EWELL. 



Laboratory of the Division of Chem- 

 istry of the U. S. Department of 

 Agriculture, July 1, 1898. 



Corks and Labels. 



The corks of bottles containing alco- 

 holic specimens last only a few years, 

 soon decaying and allowing the alcohol 

 to evaporate. Labels also become mac- 

 erated if placed in alcohol, and writing 



becomes indistinct and finally so blurred 

 and faint as to be illegible. This has 

 caused many to adopt the plan of past- 

 ing the label on the outside of the bottle 

 instead of placing it Inside, where it 

 should properly be. Even if the labels 

 are made of parchment paper, they will 

 change color in the alcohol and become 

 unsightly. 



To counteract the destruction of labels 

 and corks I have for some time used 

 paraffin with entire success. The pro- 

 cess is of course very simple. After the 

 labels have been written and become 

 perfectly dry, they are dipped in melted 

 paraffin. The time of immersion should 

 be sufficient to allow the paraffin to soak 

 through the paper and make it semi- 

 transparent, from a few seconds to one 

 minute. When the label is taken out, 

 the superfluous paraffin is drained off 

 and in a few seconds more the paraffin 

 has hardened sufficiently to allow the 

 label to be placed in the bottle with the 

 alcoholic specimens. It is now practical- 

 ly indestructible and will last as long as 

 the specimens, without deteriorating in 

 color or composition. Other labels may 

 be treated in the same way. Such labels 

 can not be tampered with afterwards, 

 as the paraffin prevents the writing from 

 being destroyed or erased, and also pre- 

 vents any writing from being added to 

 the old label. 



The corks should be perfectly dry and 

 new. Place them in the boiling or melted 

 paraffin for a few minutes. The paraffin 

 will enter and fill up the pores. When 

 the cork is inserted in the bottle a string 

 should be placed at one side in order to 

 allow the air to escape, otherwise the 

 cork will not stay in the bottle,. Next a 

 small white label is stuck on the cork 

 and held there by two short pins. This 

 label need not contain anything but the 

 number and the name of the specimen. 

 The next step is to dip the neck of the 

 bottle and cork in the paraffin, thus 

 causing it to be hermetically sealed. 



Bottles treated in this manner do not 

 require refilling, as the alcohol does not 

 evaporate and their labels will always 

 remain clean and neat. 



GUSTAV ElSEN. 



California Academy of Sciences, San 

 Francisco, Cal. 



Cover glasses and slides may be 

 cleaned by immersing them in fluid 

 made by adding to a saturated aque- 

 ous solution of potassium bichromate, 

 about one-eighth of its bulk of strong 

 sulphuric acid. Allow the mixture to 

 cool before using. After the glasses 

 have remained in the solution for an 

 hour, wash thoroughly in water and dry 

 with a clean cloth. 



