THE ALUMNI JOURNAL 



305 



PRESERVATION OF flUCILAQES AND 

 PASTES. 



By Frederick Lester. 



Considerable has been written from 

 time to time about preservation of mucil- 

 ages and pastes. 



With a view of overcoming this diflfi- 

 culty I began a line of experiments. 



Experiment No i, — (Date, January 20, 

 1896). — Mix 8 ounces of flour and 4 pints 

 of cold water, and stir till free from lump, 

 add one-half ounce of pulverized alum, 

 stir thoroughly and place in the water- 

 bath and boil till of proper thicknes; then 

 transfer to an earthenware jar, and when 

 cool stir in one-half ounce of a 40 per 

 cent, solution of formaldehyde. This 

 has stood from the time made till May 10, 

 in the jar, covered but not sealed, and at 

 present writing 1 am using this paste as 

 sweet and in as good condition as when 

 first made. 



Experiment No. 2. — Take of gelatin, 

 I ounce; flour, 4 ounces; water, 3 pints; 

 formaldehyde, y% ounce. Cover the gel- 

 atin with one pint of water and allow it 

 to soften, then heat to dissolve, mix this 

 with the flour and 2 pints of water prev- 

 iously made into paste, and boil them. 

 When cool mix with the formaldehyde. 

 This paste at the end of sixty days show- 

 ed no signs of spoiling, being fresh and 

 sweet, although it had been exposed to a 

 summer temperature all the time. Still, 

 it was necessary to keep it covered when 

 not in use. A portion that was left un- 

 covered for a week became watery. 



Experiment No. 3. — Mix starch, 2 

 ounces, and water, 16 ounces and make 

 a paste by heating. When cool add Y^ 

 ounce of formaldehyde. This was made 

 on the same day as No. 2 and subject to 

 the same conditions. It is in perfect 

 condition at the present writing. 



Experiment No. 4. — Mucilage of acacia 



U. S. P. was made and one per cent, of 

 formaldehyde added. This has now been 



standing for two months in a warm place 

 and show no signs of fermentation. 



These experiments covered the entire 

 ground that I had intended to cover and, 

 demonstrated beyond question the pre- 

 servative effect of formaldehyde. But 

 wishing to extend my researches still 

 further, the following experiments were 

 made: 



Experiment No. 5. — Make a thick 

 paste from white dextrim, 4 ounces; and 

 water, as much as required. Then add 

 8 ounces of flour paste made as in ex- 

 periment No. I, and Y ounce of for- 

 maldehyde. This has been setting on 

 on the shelf for more than forty days and 

 is as sweet as when first made. 



Experiment No. 6. — To paste made as 

 in No 5, but half the quantity of for- 

 maldehyde was added. This kept equally 

 well. Thus it can be readily seen that 

 by the use of formaldehyde paste or 

 mucilage can be kept for months. Ex- 

 perient No. i shows a flour paste good 

 after six months' standing. Part of it 

 was placed in an open jar tor use and re- 

 mained sweet till used up. The rest 

 was placed in a covered jar and is as nice 

 at this writing as when first made. 

 Most of these experiments were made 

 with covered jars, but no effort was 

 made to seal them. They were placed 

 on the shelf and subject to the warm 

 summer atmosphere of the room. — W.D. 

 Reprinted from the Moyit. Phar. Jour. 



M. K. Olszewski has found that 

 helium cannot be liquified by the most 

 powerful methods yet available. It is 

 more permanent than hydrogen, probably 

 owing to its monatomic structure, and is 

 on that account valuable as a thermetric 

 substance at very low temperatures. A 

 comparison of a helium and a hydrogen 

 thermometer shows, however, that hy- 

 drogen has normal expansion as far as 

 — 234.5° C, its critical temperature, and 

 is therefore available for thermometric 

 use down to that point. — Scien. American. 



