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Toua laa autroa axampiaira* originaux sont filmte an commandant par la pramiAro paga qui comporta una amprainta d'impraaaion ou d'illustration at an tarminant par la darniira paga qui comporta una talla amprainta. Un das symbolas suivants ipparaitra sur la darniAra imaga da chaqua microficha, salon la cas: la symbola — «>signifia "A SUIVRE". la symbola ▼ signifia "FIN". Las cartas, planrhas. tablaaux, ate. pauvant itra filmis i das taux da reduction diffirants. Lorsqua la document ast trop grand pour itra raproduit •n un saul cliche, il ast film* i partir da I'angla supAriaur gaucha. da gaucha h droita. at da haut an baa, an pranant la nombra d'imagas nicassaira. Las diagrammas suivants illustrant la mAthoda. 2 3 5 6 FOODS AND DRUGS LABORATORY •■*-ii or THE DEPARTMENT OF TRADE AND COMMERCE OTTAWA, CANADA BULLETIN No. 419 WATER GLASS (SODIXJM SILICATE.) 54085-^ . •! m \r •r is ! \ NOTES AND COMMENTS. Under this heading, as occaaion affaea, the Bulletins iistied by this Departmeot will contain, as an appendix, such conunent as may seem necessary or advisable upon matters relating to the woric of the Department in connection with the administration of the Adulteration Act, the Fertilizers Act, the Feeding Stuffs Act or the Proprietary Medicines Act. It frequently haiq>en8 that correspondents aak information regarding the aboTe Acts, of such nature that the matter in question possesses general interest, and comment ui>on it would prove acceptable and useful to others than the immediate questioner. In such cases the reply may find a place in these columns. For con- Tonienoe of reference these notes will be numbered in series. .< ■' Antdyit. FOODS AND DRUGS mant upon ition Btary iboTe and diat« oon- LABORATORY or THE DEPARTMENT OF TRADE AND COMMERCE OTTAWA, CANADA BULLETIN No. 419 WATER GLASS (Sodium Silicate.) Ottawa, January 3, 191!». F. C. T. (yilARA. Esq.. Deputy Minister of Trade ond Commerce. SiB,-=-Water Glass (esseatially sodium silicate) is not a food; but it has coine to be so largely* used as a preservative for eggs and its relation to this most important food is so very close, that a special report in connection therewith it justified. My attention was first called to the article by ii letter of date 27th April. 191M. It was pointed out that Water Glass as sold in Canada was a very variable article, sometimes thin, sometimes quite thick and viscous; while the quantity supplied in tins of similar size varied considerably. It was further stated that, while excellent results in egg-preservation were commonly obtained, a considerable numbec of failures had occurred, presumably due to the too groat dilution of the preservative liquid. The following directions for the use of Water Glass are given in the Weekly News Letter of 14 August, 1918 (Dept of Agriculture, U.S.A.)— "Dissolve 1 quart of Sodium Silicate in 9 quazts of watw. This is 8i5ffi- oient for 15 dozen eggs." It will be seen in the sequel that the amount of actuc - sodium silicate contained in the solutions on our markets varies from about 30 i*r cent, to about 55 per cent. If the user of the article is led to believe that he is dealing with actual sodium silicate, it is manifest that serious mistakes must be made. > The standardization of commercial water glass is therefore necessary and I believe that the excellent report furnished by Mr. Rowat of this staff, to whom this investigation was entrusted, will be found sufficiently complete to enable your Advisory Board to recommend practicable standards. It may be well here to state that both vaseline and lime water have been found to be ifairly satisfactory in the preservation of eggs. Dr. Longworthy, (Fanners' Bulletin No. 128, Dept. of Agriculture, U.S.A.,) says: "Some of the eggs were iwn I ^9^ Ir i: ivl if f lln. ., ir^ 4: "i I \ ■ f' i ;, f Ttrnuhfld with TMaline; thr • w«ra all good, h w«n tliOM prwinreJ in Uhm watv, or in a lolntion of watar glats. Of the last thiae method^ jnaacrratifm In a lohition of water glais ii eipedally reconunended, ainoo rarniahing the ^s* with viwolin* ia time^oniuniing, and treatment with lime water sometimea coinmutiicatea to the eegs a disagreeable odour and taste." Dr. Shutt of the Experimental Farms, Ottawa, (Exhibition Oiroular No. 49, January. 1916) has experimented with more than twenty-flTo diflfownt preparationa as egg-preserratiTes, and he giyes preference to lime water, giving water glass the second placa There can be little doubt that much of the complaint heard as to the unsatisfactory character of eggs which hare been subjected to one or another rariaty of preservatire treatment, is due to the fact that the eggs have not been strictly fresh in the first instance. A stale egg is a witness to the efficacy of its preserrative treat- ment when it turns out a stale egg. Only strictly new laid eggs should be subjected to any preservative process. I beg to recommend publication of Mr. Rowat's letter and the accompanying table of analytical resulto as Bulletin No. 419, both for the information of the public, and as a basis for the standardization of Water Qlass. I have the honour to be, Sir, Your obedient servant, Db. a MoGill, Chief Analyst, , Ottawa, Ont. A. MoOnXk Chief Analy$t. Dear sib,— I beg to sutaiit the following report, dealing with the analysis of 71 samples of Water Glass, collected on the order of July last. Of those samples, 8 were analysed at Halifax, 22 at Winnipeg. 3 at Vancouver and the remainder at Ottawa. This is the first occasion that this material has been subjected to oxamination in these laboratories, hence a brief review will be madd of the nature of water gUus. Water glass is not a pure chemical corapound; it is not a chemical individual. The product marketed under this name is usually a concentrated solution of mizeil silicates of soda, and m pre-war days, it also frequently contained silicate of potassium. It is usually prepared by fusing 2 parts of sand with 1 part of carbonate of soda and 01 part of charcoal. Sodium hydroxide or sulphate sometimes rqilace the car- bonate. After fusion, the glass like mass which has beau formed ia broken up, leached with hot water, and the resulting solution evaporated to a viscous syrup. This syrup is the article commonly sold as water-glass. The solution containa an indefinite mix- ture of the ortho and meta-silicatea of sodium, and the constitution of the dry material varies between the limits Na,0.2SiO, and Na,0.4SiOj. The chief impurities found in commercial water-glass are chlorides, sulphates, and small amounts of inm. These are frequently present to the extent of 2 per cent or more. Sodium silicates have long been used for importing a fireproof character to «.od and other materials, and more recently for producing artifidal stone for building pur- poses, and for a peculiar kind of permanent fresco-painting (stereochromy) the results of which are intended to withstand exposure to the weather. Its more common use in rural communities, however, is as an Egg-Freaerver. For this purpose^ this substance has b«en ahown to be, all things considered, decidedly the best known at the present tin* l»i««»^w»yin«ip««iwkcl«»ttd«MytoUiidkk«uldo«i«,l«,doB^ «1^ ««I •«» d«dod^ t««l to impm «v iHrtloerid. «.ro, „d w pNii,^ wiU mnmin in Mtiifactoi, condition for • ymt. «id «T«a lomw The o^ooHcnt reputation which thi, matter enjoy, has .reated a .■ou.ideraMe d«ii»d for it uid M > aaturri oonioquaioe • nmnber of iMnuf«rtur« 1i>t« Moh pUcod upon the market a i>rand of water-glati 8in