Once upon a time, in a far off land known as Canada, there was a recovering chemist named Darcy O'Neil. One day, he took his chemist skills, married them with his appreciation for bar-tending and vintage cocktails, and created the website Art of Drink, which would become one the most visited of all cocktail blogs on the Web. One of the more recent of Darcy's undertakings has been exploring the lost art of the soda fountain, which he did first on his site, and then in a book published at the end of last year, Fix the Pumps. Most recently, his new passion garnered the attention of Imbibe Magazine, which did a feature on Darcy and the now somewhat reviving phenomenon of the soda fountain (at least in a few cities) in their July/August 2011 issue. Fix the Pumps is a great read (and Art of Drink a great resource). It gives a fascinating historical account of the rise and eventual fading away of the soda fountain in the late 19th and early 20th Century, including accounts of, and recipes for, a wide variety of interesting drink forms that the average person has never even heard of. One such drink form is the phosphate.Phosphates were a popular form of soda fountain drink in the late 18th and early 19th Centuries that were characterized by the addition of "acid phosphate" as a key ingredient. Acid phosphate in turn is a liquid composed of phosphoric acid, phosphate salts of calcium, magnesium, potassium, and sodium. As with many such beverage concoctions, acid phosphate started out as a popular medicinal additive, and was proclaimed to cure sundry ailments ranging from indigestion to "sexual exhaustion." There's quite a bit of other interesting history, but I leave you to pick up a copy of Fix the Pumps for it.Darcy has actually been producing acid phosphate some other exciting extinct ingredients for sale, most recently under the moniker Extinct Chemical. Alas, however, with the operation being based out of Canada, they were not the easiest thing to procure for this Boston boozehound. HOWEVER, a short time ago I became aware that The Boston Shaker has started stocking some of these products, including acid phosphate. So of course, I picked up a bottle to play with.As far as the initial question you might have of what exactly does acid phosphate taste like, it has a tartness to it that's reminiscent of tart candy. I would say it's a little sweet as well, or at least "tangy." I've heard acid phosphate described as something you can use as a substitute for citrus or sour fruit to provide tartness, although I wonder if that's a bit deceptive. Many of the recipes for phosphates in Fix the Pumps and other sources often include both acid phosphate AND a sour fruit flavoring agent, e.g. syrup made with lemon juice or oil, or sour cherry syrup. Perhaps it could be said that it's either a substitute for tart fruit flavor, or something that can amplify the tartness of tart fruit flavoring agents? In any event, I of course had to make a drink with the stuff.For my first phosphate, I went with the Angostura Phosphate, the first recipe listed in Fix the Pumps under the phosphate heading. It is also the recipe mentioned by Imbibe magazine in their discussion of phosphates (perhaps they too didn't really know what direction to go in so they went alphabetic? Great minds think alike. Or maybe just lazy minds).Angostura Phosphate1 oz. Lemon Syrup (see below)1 tsp Angostura Bitters1/2 tsp Acid Phosphate7 oz. carbonated water- Combine ingredients in a highball glass with cracked ice.- Stir and serveFor the lemon syrup, Darcy has one recipe up on Art of Drink that's probably a little easier to work with in some ways compared to what I used (and in some ways not). I used the recipe for lemon syrup in Fix the Pumps but reduced the yield. This recipe in turn calls for "soda foam" as an ingredient. Soda foam is basically an additive that causes more foaming/frothing in the end product. Fix the Pumps has recipes for a couple different variants of Soda Foam. The one for which I had ingredients on hand was a gum arabic/water solution. Quick note on gum arabic: I find it to be a huge pain in the butt. It's a pain to acquire (try online or at a specialty health food/spice store; it's also called acacia powder), not especially cheap, and from my experience not the easiest thing in the world to work with (also, you have to make sure you are getting food grade). I will leave a further lecture on that for another day, and merely put out the warning that recipes using it are not really for the feint of heart, or those handicapped in terms of cooking skill or patience (perhaps I'm just one or both of those?). It's worth mentioning that I don't think it would be the end of the world to leave out the soda foam altogether in this recipe. In all likelihood, you don't actually have a vintage soda fountain to mix up this drink, so the foaming is not going to compare in any event. Usually adding some gum arabic to a syrup used in a cocktail will give you a bit of a thicker mouthfeel to the beverage; in this case, however, I think the amount is so small that I don't think this the gum arabic is the keystone of the drink recipe by any means.So, with my slight alterations/suggestions:Lemon Syrup8 oz. fresh lemon juice1 oz. lemon zest12 oz. sugar1 1/2 tsp. soda foam- Bring lemon juice to a boil in a pot- Remove lemon juice from the heat and add in the lemon peel/zest- Cover post and let stand until cold- Strain/filter and add filtered water, sufficient to bring volume up to 1 cup of liquid- Dissolve sugar in the liquid and add in soda foam- For good measure, I filtered again through a coffee filterSoda Foam (Gum Arabic solution)2 oz. gum arabic4 oz. filtered water- slowly add gum arabic to room temp/cold filtered water, stirring while adding- once dissolved, let sit for approximately 1 hr- skim off any precipitate that forms at the top, then filter through a coffee filter or other mechanismResults:This is a very tasty beverage! You get quite a bit of the spice flavor from the Angostura, but at the same time it's not overly sweet, sour, or bitter; a nice bit of balance. I dare say I might even go so far as to call it dry, in the positive sense associated with good cocktails, which is pretty surprising for a drink that's still predominantly flavored syrup and soda. Not a bad start!
read more: A First Forfay Into Phosphates