A gerb is a firework that shoots flame and sometimes sparks. When set in the ground and directed upward, a gerb is called a fountain. This particular gerb, while not spectacular, is pretty and gives a long lasting effect.
Case: Roll this to desired length and diameter (I often use 3/8" dia. and 5" long) from any kraft paper. It need not be particularly thick walled, and in fact a wall not much thicker than that required for a lance is preferable. Because of the slow composition and hot titanium sparks, the case will usually burn down as the device performs; the thinner the case, the less its flame interferes with the red of the compo. An inner single turn of aluminum foil on the former slows it a little, and sodium silicate (water glass) instead of my usual Elmer's Glue-All also helps, but even both in combination only retard the process enough to preserve the jet effect. You're not going to be able to reuse the tube, but the jet may benefit from a thicker wall if sodium silicate is used. The case is not choked.
The plug may be of water putty or wadded-paper-and-glue. (The more expensive Durham's Rock Hard wets faster and is therefore easier to mix than other water putties, but they dry just as hard.) Putty may be formed into a point to press into the ground. Otherwise a corrugated cardboard base may be attached. The attachment of water putty to cardboard is weak; it's better with Elmer's Glue-All or hot melt glue.
Sr(NO3)2 .............3 parts
KClO4 ...................2 parts
red gum................1 part
The above powders are mixed dry. Parts are by weight; however, the mixture is dense and does not compress much.
To the above, flake titanium passing 20 but not 40 mesh (i.e. 20-40 mesh Ti flake) is added "to taste" just before, or in the funnel as, the case is charged. (Don't try to prepare a quantity in advance; the metal will sift out of the dry powders.) You'll find that not nearly as many sparks are seen as you'd expect from a given number of flakes, so be more generous than you think you need with the Ti. This is hand pressed with a wood dowel or unsharpened pencil thru the funnel. Note that Ti is a hard metal and coarse flakes have the capacity to strike fire.
The compo lights easily from visco fuse or black match pressed in with the last increment or two. No starting fire is needed.
The bright white Ti sparks sizzle as they burst after traveling upward from this composition's red flame. The burst is of the type designated "flower" by Shimizu in Pyrotechnica 7. Caution: coarse titanium isn't sparkler material; these sparks are hot!
This gerb can also be effective as one of a bundle or battery of fountain & candle tubes. Its effect being slow, the timing should be taken into account. However, it will almost surely set fire to the entire set of discharged cases at the end. One way to make use of combined effects is to have it as a stage in a tube charged with different compositions. For instance, a case with whistle mix on top can whistle and quickly burn down to the red Ti stage, which may then benefit by jetting thru the length of emptied case before burning thru.